Re: DRM Atomic property for color-space conversion

[Hans Verkuil]

On 03/17/2017 03:09 PM, Ville Syrjälä wrote:
> On Fri, Mar 17, 2017 at 10:33:15AM +, Brian Starkey wrote:
>> For not-programmable hardware, would a second "DEGAMMA_FIXED" property
>> make sense, which is an enum type exposing what curves are supported?
>> (with analogous GAMMA_FIXED as well)
> 
> Hmm. I suppose we could make it a bit more explicit like that.
> Not sure how we'd specify those though. Just BT.709, BT.2020, etc. and
> perhaps just something like 'Gamma 2.2' if it's a pure gamma curve?
> Someone who is more familiar with the subject could probably propose
> a better naming scheme.

Just as a reference, this is how V4L2 describes colorspace information:

https://www.linuxtv.org/downloads/v4l-dvb-apis-new/uapi/v4l/colorspaces.html

Sections 2.4-2.6 are all about that.

Note: pure gamma functions (i.e. Gamma 2.2) are not defined since we do not
support hardware that needs that. Should that be needed in the future, then
we would add that to the xfer_func defines.

Regards,

Hans

Re: DRM Atomic property for color-space conversion

[Hans Verkuil]

On 03/17/2017 03:09 PM, Ville Syrjälä wrote:
> On Fri, Mar 17, 2017 at 10:33:15AM +, Brian Starkey wrote:
>> For not-programmable hardware, would a second "DEGAMMA_FIXED" property
>> make sense, which is an enum type exposing what curves are supported?
>> (with analogous GAMMA_FIXED as well)
> 
> Hmm. I suppose we could make it a bit more explicit like that.
> Not sure how we'd specify those though. Just BT.709, BT.2020, etc. and
> perhaps just something like 'Gamma 2.2' if it's a pure gamma curve?
> Someone who is more familiar with the subject could probably propose
> a better naming scheme.

Just as a reference, this is how V4L2 describes colorspace information:

https://www.linuxtv.org/downloads/v4l-dvb-apis-new/uapi/v4l/colorspaces.html

Sections 2.4-2.6 are all about that.

Note: pure gamma functions (i.e. Gamma 2.2) are not defined since we do not
support hardware that needs that. Should that be needed in the future, then
we would add that to the xfer_func defines.

Regards,

Hans

Re: DRM Atomic property for color-space conversion

[Ville Syrjälä]

On Fri, Mar 17, 2017 at 10:33:15AM +, Brian Starkey wrote:
> Hi Ville,
> 
> On Thu, Mar 16, 2017 at 07:36:56PM +0200, Ville Syrjälä wrote:
> >On Thu, Mar 16, 2017 at 07:05:12PM +0200, Sharma, Shashank wrote:
> >> On 3/16/2017 5:55 PM, Brian Starkey wrote:
> >> > On Thu, Mar 16, 2017 at 05:14:07PM +0200, Sharma Shashank wrote:
> >> >> On 3/16/2017 4:37 PM, Local user for Liviu Dudau wrote:
> >> >>> On Thu, Mar 16, 2017 at 04:30:59PM +0200, Ville Syrjälä wrote:
> >>  On Thu, Mar 16, 2017 at 04:20:29PM +0200, Sharma, Shashank wrote:
> >> > On 3/16/2017 4:07 PM, Ville Syrjälä wrote:
> 
> [snip]
> 
> >> >>
> >> >> So what we might need is something like:
> >> >> enum YCBCR_TO_RGB_CSC
> >> >>   * YCbCr BT.601 limited to RGB BT.709 full
> >> >>   * YCbCr BT.709 limited to RGB BT.709 full  >> >> likely default value IMO>
> >> >>   * YCbCr BT.601 limited to RGB BT.2020 full
> >> >>   * YCbCr BT.709 limited to RGB BT.2020 full
> >> >>   * YCbCr BT.2020 limited to RGB BT.2020 full
> >> >>
> >> >> And thanks to BT.2020 we'll need a RGB->RGB CSC property as well.
> >> >> Eg:
> >> >> enum RGB_TO_RGB_CSC
> >> >>   * bypass (or separate 709->709, 2020->2020?)  >> >> default>
> >> >>   * RGB BT.709 full to RGB BT.2020 full
> >> >
> >> > I like this approach, from a point of view of being explicit and
> >> > discoverable by userspace. It also happens to map quite nicely to our
> >> > hardware... we have a matrix before degamma, so we could do a
> >> > CSC + Gamut conversion there in one go, which is apparently not 100%
> >> > mathematically correct, but in general is good enough.
> >> >
> >> > ... however having talked this over a bit with someone who understands
> >> > the detail a lot better than me, it sounds like the "correct" thing to
> >> > do as per the spec is:
> >> >
> >> > CSC -> DEGAMMA -> GAMUT
> >> >
> >> > e.g.
> >> >
> >> > YCbCr bt.601 limited to RGB bt.601 full -> degamma ->
> >> > RGB bt.601 full to RGB bt.709 full
> >> >
> >> > So that sounds like what we need to support in the API, and also
> >> > sounds more like the "separate properties" approach.
> >> I agree.
> >> >
> >> >>
> >> >> Alternatives would involve two properties to define the input and
> >> >> output
> >> >> from the CSC separately, but then you lose the capability to see
> >> >> which
> >> >> combinations are actually supoorted.
> >> > I was thinking about this too, or would it make more sense to
> >> > create two
> >> > properties:
> >> > - one for gamut mapping (cases like RGB709->RGB2020)
> >> > - other one for Color space conversion (cases lile YUV 709 -> RGB
> >> > 709)
> >> >
> >> > Gamut mapping can represent any of the fix function mapping,
> >> > wereas CSC
> >> > can bring up any programmable matrix
> >> >
> >> > Internally these properties can use the same HW unit or even same
> >> > function.
> >> > Does it sound any good ?
> >> >
> >> > It seems to me that actually the two approaches can be combined into
> >> > the same thing:
> >> >  * We definitely need a YCbCr-to-RGB conversion before degamma
> >> >(for converting YUV data to RGB, in some flavour)
> >> >  * We definitely need an RGB-to-RGB conversion after gamma to handle
> >> >709 layers blended with Rec.2020.
> >> > The exact conversion each of those properties represents (CSC + gamut,
> >> > CSC only, gamut only) can be implicit in the enum name.
> >> >
> >> > For hardware which has a fixed-function CSC before DEGAMMA with a
> >> > matrix after DEGAMMA, I'd expect to see something like below. None of
> >> > the YCBCR_TO_RGB_CSC values include a gamut conversion, because that
> >> > is instead exposed with the RGB_TO_RGB_CSC property (which represents
> >> > the hardware matrix)
> >> >
> >> > YCBCR_TO_RGB_CSC (before DEGAMMA):
> >> > YCbCr BT.601 limited to RGB BT.601 full
> >> > YCbCr BT.709 limited to RGB BT.709 full
> >> > YCbCr BT.2020 limited to RGB BT.2020 full
> >> >
> >> > RGB_TO_RGB_CSC (after DEGAMMA):
> >> > RGB BT.601 full to RGB BT.709 full
> >> > RGB BT.709 full to RGB BT.2020 full
> >> >
> >> >
> >> > On the other hand, on hardware which does a CSC + Gamut conversion in
> >> > one go, before DEGAMMA (like ours), you might have:
> >> >
> >> > YCBCR_TO_RGB_CSC (before DEGAMMA):
> >> > YCbCr BT.601 limited to RGB BT.601 full
> >> > YCbCr BT.601 limited to RGB BT.709 full
> >> > YCbCr BT.709 limited to RGB BT.709 full
> >> > YCbCr BT.2020 limited to RGB BT.2020 full
> >> >
> >> > RGB_TO_RGB_CSC (after DEGAMMA):
> >> > Not supported
> >> >
> >> > Userspace can parse the two properties to figure out its options to
> >> > get from desired input -> desired output. It is perhaps a little
> >> > verbose, but it's descriptive and flexible.
> >> >
> >> Seems to be a good idea, Ville ?
> >
> >Looks pretty sane to me.
> >
> >Though how we'll do the degamma/gamma is 

Re: DRM Atomic property for color-space conversion

[Ville Syrjälä]

On Fri, Mar 17, 2017 at 10:33:15AM +, Brian Starkey wrote:
> Hi Ville,
> 
> On Thu, Mar 16, 2017 at 07:36:56PM +0200, Ville Syrjälä wrote:
> >On Thu, Mar 16, 2017 at 07:05:12PM +0200, Sharma, Shashank wrote:
> >> On 3/16/2017 5:55 PM, Brian Starkey wrote:
> >> > On Thu, Mar 16, 2017 at 05:14:07PM +0200, Sharma Shashank wrote:
> >> >> On 3/16/2017 4:37 PM, Local user for Liviu Dudau wrote:
> >> >>> On Thu, Mar 16, 2017 at 04:30:59PM +0200, Ville Syrjälä wrote:
> >>  On Thu, Mar 16, 2017 at 04:20:29PM +0200, Sharma, Shashank wrote:
> >> > On 3/16/2017 4:07 PM, Ville Syrjälä wrote:
> 
> [snip]
> 
> >> >>
> >> >> So what we might need is something like:
> >> >> enum YCBCR_TO_RGB_CSC
> >> >>   * YCbCr BT.601 limited to RGB BT.709 full
> >> >>   * YCbCr BT.709 limited to RGB BT.709 full  >> >> likely default value IMO>
> >> >>   * YCbCr BT.601 limited to RGB BT.2020 full
> >> >>   * YCbCr BT.709 limited to RGB BT.2020 full
> >> >>   * YCbCr BT.2020 limited to RGB BT.2020 full
> >> >>
> >> >> And thanks to BT.2020 we'll need a RGB->RGB CSC property as well.
> >> >> Eg:
> >> >> enum RGB_TO_RGB_CSC
> >> >>   * bypass (or separate 709->709, 2020->2020?)  >> >> default>
> >> >>   * RGB BT.709 full to RGB BT.2020 full
> >> >
> >> > I like this approach, from a point of view of being explicit and
> >> > discoverable by userspace. It also happens to map quite nicely to our
> >> > hardware... we have a matrix before degamma, so we could do a
> >> > CSC + Gamut conversion there in one go, which is apparently not 100%
> >> > mathematically correct, but in general is good enough.
> >> >
> >> > ... however having talked this over a bit with someone who understands
> >> > the detail a lot better than me, it sounds like the "correct" thing to
> >> > do as per the spec is:
> >> >
> >> > CSC -> DEGAMMA -> GAMUT
> >> >
> >> > e.g.
> >> >
> >> > YCbCr bt.601 limited to RGB bt.601 full -> degamma ->
> >> > RGB bt.601 full to RGB bt.709 full
> >> >
> >> > So that sounds like what we need to support in the API, and also
> >> > sounds more like the "separate properties" approach.
> >> I agree.
> >> >
> >> >>
> >> >> Alternatives would involve two properties to define the input and
> >> >> output
> >> >> from the CSC separately, but then you lose the capability to see
> >> >> which
> >> >> combinations are actually supoorted.
> >> > I was thinking about this too, or would it make more sense to
> >> > create two
> >> > properties:
> >> > - one for gamut mapping (cases like RGB709->RGB2020)
> >> > - other one for Color space conversion (cases lile YUV 709 -> RGB
> >> > 709)
> >> >
> >> > Gamut mapping can represent any of the fix function mapping,
> >> > wereas CSC
> >> > can bring up any programmable matrix
> >> >
> >> > Internally these properties can use the same HW unit or even same
> >> > function.
> >> > Does it sound any good ?
> >> >
> >> > It seems to me that actually the two approaches can be combined into
> >> > the same thing:
> >> >  * We definitely need a YCbCr-to-RGB conversion before degamma
> >> >(for converting YUV data to RGB, in some flavour)
> >> >  * We definitely need an RGB-to-RGB conversion after gamma to handle
> >> >709 layers blended with Rec.2020.
> >> > The exact conversion each of those properties represents (CSC + gamut,
> >> > CSC only, gamut only) can be implicit in the enum name.
> >> >
> >> > For hardware which has a fixed-function CSC before DEGAMMA with a
> >> > matrix after DEGAMMA, I'd expect to see something like below. None of
> >> > the YCBCR_TO_RGB_CSC values include a gamut conversion, because that
> >> > is instead exposed with the RGB_TO_RGB_CSC property (which represents
> >> > the hardware matrix)
> >> >
> >> > YCBCR_TO_RGB_CSC (before DEGAMMA):
> >> > YCbCr BT.601 limited to RGB BT.601 full
> >> > YCbCr BT.709 limited to RGB BT.709 full
> >> > YCbCr BT.2020 limited to RGB BT.2020 full
> >> >
> >> > RGB_TO_RGB_CSC (after DEGAMMA):
> >> > RGB BT.601 full to RGB BT.709 full
> >> > RGB BT.709 full to RGB BT.2020 full
> >> >
> >> >
> >> > On the other hand, on hardware which does a CSC + Gamut conversion in
> >> > one go, before DEGAMMA (like ours), you might have:
> >> >
> >> > YCBCR_TO_RGB_CSC (before DEGAMMA):
> >> > YCbCr BT.601 limited to RGB BT.601 full
> >> > YCbCr BT.601 limited to RGB BT.709 full
> >> > YCbCr BT.709 limited to RGB BT.709 full
> >> > YCbCr BT.2020 limited to RGB BT.2020 full
> >> >
> >> > RGB_TO_RGB_CSC (after DEGAMMA):
> >> > Not supported
> >> >
> >> > Userspace can parse the two properties to figure out its options to
> >> > get from desired input -> desired output. It is perhaps a little
> >> > verbose, but it's descriptive and flexible.
> >> >
> >> Seems to be a good idea, Ville ?
> >
> >Looks pretty sane to me.
> >
> >Though how we'll do the degamma/gamma is 

Re: DRM Atomic property for color-space conversion

[Brian Starkey]

Hi Ville,

On Thu, Mar 16, 2017 at 07:36:56PM +0200, Ville Syrjälä wrote:

On Thu, Mar 16, 2017 at 07:05:12PM +0200, Sharma, Shashank wrote:

On 3/16/2017 5:55 PM, Brian Starkey wrote:
> On Thu, Mar 16, 2017 at 05:14:07PM +0200, Sharma Shashank wrote:
>> On 3/16/2017 4:37 PM, Local user for Liviu Dudau wrote:
>>> On Thu, Mar 16, 2017 at 04:30:59PM +0200, Ville Syrjälä wrote:
 On Thu, Mar 16, 2017 at 04:20:29PM +0200, Sharma, Shashank wrote:
> On 3/16/2017 4:07 PM, Ville Syrjälä wrote:


[snip]


>>
>> So what we might need is something like:
>> enum YCBCR_TO_RGB_CSC
>>   * YCbCr BT.601 limited to RGB BT.709 full
>>   * YCbCr BT.709 limited to RGB BT.709 full > likely default value IMO>
>>   * YCbCr BT.601 limited to RGB BT.2020 full
>>   * YCbCr BT.709 limited to RGB BT.2020 full
>>   * YCbCr BT.2020 limited to RGB BT.2020 full
>>
>> And thanks to BT.2020 we'll need a RGB->RGB CSC property as well.
>> Eg:
>> enum RGB_TO_RGB_CSC
>>   * bypass (or separate 709->709, 2020->2020?) > default>
>>   * RGB BT.709 full to RGB BT.2020 full
>
> I like this approach, from a point of view of being explicit and
> discoverable by userspace. It also happens to map quite nicely to our
> hardware... we have a matrix before degamma, so we could do a
> CSC + Gamut conversion there in one go, which is apparently not 100%
> mathematically correct, but in general is good enough.
>
> ... however having talked this over a bit with someone who understands
> the detail a lot better than me, it sounds like the "correct" thing to
> do as per the spec is:
>
> CSC -> DEGAMMA -> GAMUT
>
> e.g.
>
> YCbCr bt.601 limited to RGB bt.601 full -> degamma ->
> RGB bt.601 full to RGB bt.709 full
>
> So that sounds like what we need to support in the API, and also
> sounds more like the "separate properties" approach.
I agree.
>
>>
>> Alternatives would involve two properties to define the input and
>> output
>> from the CSC separately, but then you lose the capability to see
>> which
>> combinations are actually supoorted.
> I was thinking about this too, or would it make more sense to
> create two
> properties:
> - one for gamut mapping (cases like RGB709->RGB2020)
> - other one for Color space conversion (cases lile YUV 709 -> RGB
> 709)
>
> Gamut mapping can represent any of the fix function mapping,
> wereas CSC
> can bring up any programmable matrix
>
> Internally these properties can use the same HW unit or even same
> function.
> Does it sound any good ?
>
> It seems to me that actually the two approaches can be combined into
> the same thing:
>  * We definitely need a YCbCr-to-RGB conversion before degamma
>(for converting YUV data to RGB, in some flavour)
>  * We definitely need an RGB-to-RGB conversion after gamma to handle
>709 layers blended with Rec.2020.
> The exact conversion each of those properties represents (CSC + gamut,
> CSC only, gamut only) can be implicit in the enum name.
>
> For hardware which has a fixed-function CSC before DEGAMMA with a
> matrix after DEGAMMA, I'd expect to see something like below. None of
> the YCBCR_TO_RGB_CSC values include a gamut conversion, because that
> is instead exposed with the RGB_TO_RGB_CSC property (which represents
> the hardware matrix)
>
> YCBCR_TO_RGB_CSC (before DEGAMMA):
> YCbCr BT.601 limited to RGB BT.601 full
> YCbCr BT.709 limited to RGB BT.709 full
> YCbCr BT.2020 limited to RGB BT.2020 full
>
> RGB_TO_RGB_CSC (after DEGAMMA):
> RGB BT.601 full to RGB BT.709 full
> RGB BT.709 full to RGB BT.2020 full
>
>
> On the other hand, on hardware which does a CSC + Gamut conversion in
> one go, before DEGAMMA (like ours), you might have:
>
> YCBCR_TO_RGB_CSC (before DEGAMMA):
> YCbCr BT.601 limited to RGB BT.601 full
> YCbCr BT.601 limited to RGB BT.709 full
> YCbCr BT.709 limited to RGB BT.709 full
> YCbCr BT.2020 limited to RGB BT.2020 full
>
> RGB_TO_RGB_CSC (after DEGAMMA):
> Not supported
>
> Userspace can parse the two properties to figure out its options to
> get from desired input -> desired output. It is perhaps a little
> verbose, but it's descriptive and flexible.
>
Seems to be a good idea, Ville ?


Looks pretty sane to me.

Though how we'll do the degamma/gamma is rather unclear still.

I think we might be looking at two variants of hardware:
- A fully programmable one with separate stages:
 csc -> degamma -> gamut -> gamma
- A totally fixed one with just a few different variants
 of the pipeline baked into the hardware

If we want to expose the gamma/degamma to the user, how exactly are we
going to do that with the latter form or hardware. I guess we could
specify that if the degamma property is not exposed, there will be an
implicit degamma stage between the two csc and gamut. And if it is
exposed the output from the first csc is non-linear and thus needs
the degamma 

Re: DRM Atomic property for color-space conversion

[Brian Starkey]

Hi Ville,

On Thu, Mar 16, 2017 at 07:36:56PM +0200, Ville Syrjälä wrote:

On Thu, Mar 16, 2017 at 07:05:12PM +0200, Sharma, Shashank wrote:

On 3/16/2017 5:55 PM, Brian Starkey wrote:
> On Thu, Mar 16, 2017 at 05:14:07PM +0200, Sharma Shashank wrote:
>> On 3/16/2017 4:37 PM, Local user for Liviu Dudau wrote:
>>> On Thu, Mar 16, 2017 at 04:30:59PM +0200, Ville Syrjälä wrote:
 On Thu, Mar 16, 2017 at 04:20:29PM +0200, Sharma, Shashank wrote:
> On 3/16/2017 4:07 PM, Ville Syrjälä wrote:


[snip]


>>
>> So what we might need is something like:
>> enum YCBCR_TO_RGB_CSC
>>   * YCbCr BT.601 limited to RGB BT.709 full
>>   * YCbCr BT.709 limited to RGB BT.709 full > likely default value IMO>
>>   * YCbCr BT.601 limited to RGB BT.2020 full
>>   * YCbCr BT.709 limited to RGB BT.2020 full
>>   * YCbCr BT.2020 limited to RGB BT.2020 full
>>
>> And thanks to BT.2020 we'll need a RGB->RGB CSC property as well.
>> Eg:
>> enum RGB_TO_RGB_CSC
>>   * bypass (or separate 709->709, 2020->2020?) > default>
>>   * RGB BT.709 full to RGB BT.2020 full
>
> I like this approach, from a point of view of being explicit and
> discoverable by userspace. It also happens to map quite nicely to our
> hardware... we have a matrix before degamma, so we could do a
> CSC + Gamut conversion there in one go, which is apparently not 100%
> mathematically correct, but in general is good enough.
>
> ... however having talked this over a bit with someone who understands
> the detail a lot better than me, it sounds like the "correct" thing to
> do as per the spec is:
>
> CSC -> DEGAMMA -> GAMUT
>
> e.g.
>
> YCbCr bt.601 limited to RGB bt.601 full -> degamma ->
> RGB bt.601 full to RGB bt.709 full
>
> So that sounds like what we need to support in the API, and also
> sounds more like the "separate properties" approach.
I agree.
>
>>
>> Alternatives would involve two properties to define the input and
>> output
>> from the CSC separately, but then you lose the capability to see
>> which
>> combinations are actually supoorted.
> I was thinking about this too, or would it make more sense to
> create two
> properties:
> - one for gamut mapping (cases like RGB709->RGB2020)
> - other one for Color space conversion (cases lile YUV 709 -> RGB
> 709)
>
> Gamut mapping can represent any of the fix function mapping,
> wereas CSC
> can bring up any programmable matrix
>
> Internally these properties can use the same HW unit or even same
> function.
> Does it sound any good ?
>
> It seems to me that actually the two approaches can be combined into
> the same thing:
>  * We definitely need a YCbCr-to-RGB conversion before degamma
>(for converting YUV data to RGB, in some flavour)
>  * We definitely need an RGB-to-RGB conversion after gamma to handle
>709 layers blended with Rec.2020.
> The exact conversion each of those properties represents (CSC + gamut,
> CSC only, gamut only) can be implicit in the enum name.
>
> For hardware which has a fixed-function CSC before DEGAMMA with a
> matrix after DEGAMMA, I'd expect to see something like below. None of
> the YCBCR_TO_RGB_CSC values include a gamut conversion, because that
> is instead exposed with the RGB_TO_RGB_CSC property (which represents
> the hardware matrix)
>
> YCBCR_TO_RGB_CSC (before DEGAMMA):
> YCbCr BT.601 limited to RGB BT.601 full
> YCbCr BT.709 limited to RGB BT.709 full
> YCbCr BT.2020 limited to RGB BT.2020 full
>
> RGB_TO_RGB_CSC (after DEGAMMA):
> RGB BT.601 full to RGB BT.709 full
> RGB BT.709 full to RGB BT.2020 full
>
>
> On the other hand, on hardware which does a CSC + Gamut conversion in
> one go, before DEGAMMA (like ours), you might have:
>
> YCBCR_TO_RGB_CSC (before DEGAMMA):
> YCbCr BT.601 limited to RGB BT.601 full
> YCbCr BT.601 limited to RGB BT.709 full
> YCbCr BT.709 limited to RGB BT.709 full
> YCbCr BT.2020 limited to RGB BT.2020 full
>
> RGB_TO_RGB_CSC (after DEGAMMA):
> Not supported
>
> Userspace can parse the two properties to figure out its options to
> get from desired input -> desired output. It is perhaps a little
> verbose, but it's descriptive and flexible.
>
Seems to be a good idea, Ville ?


Looks pretty sane to me.

Though how we'll do the degamma/gamma is rather unclear still.

I think we might be looking at two variants of hardware:
- A fully programmable one with separate stages:
 csc -> degamma -> gamut -> gamma
- A totally fixed one with just a few different variants
 of the pipeline baked into the hardware

If we want to expose the gamma/degamma to the user, how exactly are we
going to do that with the latter form or hardware. I guess we could
specify that if the degamma property is not exposed, there will be an
implicit degamma stage between the two csc and gamut. And if it is
exposed the output from the first csc is non-linear and thus needs
the degamma 

Re: DRM Atomic property for color-space conversion

[Local user for Liviu Dudau]

On Thu, Mar 16, 2017 at 07:36:56PM +0200, Ville Syrjälä wrote:
> On Thu, Mar 16, 2017 at 07:05:12PM +0200, Sharma, Shashank wrote:
> > Regards
> > 
> > Shashank
> > 
> > 
> > On 3/16/2017 5:55 PM, Brian Starkey wrote:
> > > Hi,
> > >
> > > On Thu, Mar 16, 2017 at 05:14:07PM +0200, Sharma Shashank wrote:
> > >> Regards
> > >>
> > >> Shashank
> > >>
> > >>
> > >> On 3/16/2017 4:37 PM, Local user for Liviu Dudau wrote:
> > >>> On Thu, Mar 16, 2017 at 04:30:59PM +0200, Ville Syrjälä wrote:
> >  On Thu, Mar 16, 2017 at 04:20:29PM +0200, Sharma, Shashank wrote:
> > > Regards
> > >
> > > Shashank
> > >
> > >
> > > On 3/16/2017 4:07 PM, Ville Syrjälä wrote:
> > >> On Tue, Jan 31, 2017 at 03:55:41PM +, Brian Starkey wrote:
> > >>> On Tue, Jan 31, 2017 at 05:15:46PM +0200, Ville Syrjälä wrote:
> >  On Tue, Jan 31, 2017 at 12:33:29PM +, Brian Starkey wrote:
> > > Hi,
> > >
> > > On Mon, Jan 30, 2017 at 03:35:13PM +0200, Ville Syrjälä wrote:
> > >> On Fri, Jan 27, 2017 at 05:23:24PM +, Brian Starkey wrote:
> > >>> Hi,
> > >>>
> > >>> We're looking to enable the per-plane color management 
> > >>> hardware in
> > >>> Mali-DP with atomic properties, which has sparked some 
> > >>> conversation
> > >>> around how to handle YCbCr formats.
> > >>>
> > >>> As it stands today, it's assumed that a driver will 
> > >>> implicitly "do the
> > >>> right thing" to display a YCbCr buffer.
> > >>>
> > >>> YCbCr data often uses different gamma curves and signal 
> > >>> ranges (e.g.
> > >>> BT.609, BT.701, BT.2020, studio range, full-range), so its 
> > >>> desirable
> > >>> to be able to explicitly control the YCbCr to RGB conversion 
> > >>> process
> > >>> from userspace.
> > >>>
> > >>> We're proposing adding a "CSC" (color-space conversion) 
> > >>> property to
> > >>> control this - primarily per-plane for framebuffer->pipeline 
> > >>> CSC, but
> > >>> perhaps one per CRTC too for devices which have an RGB 
> > >>> pipeline and
> > >>> want to output in YUV to the display:
> > >>>
> > >>> Name: "CSC"
> > >>> Type: ENUM | ATOMIC;
> > >>> Enum values (representative):
> > >>> "default":
> > >>> Same behaviour as now. "Some kind" of YCbCr->RGB conversion
> > >>> for YCbCr buffers, bypass for RGB buffers
> > >>> "disable":
> > >>> Explicitly disable all colorspace conversion (i.e. use an
> > >>> identity matrix).
> > >>> "YCbCr to RGB: BT.709":
> > >>> Only valid for YCbCr formats. CSC in accordance with BT.709
> > >>> using [16..235] for (8-bit) luma values, and [16..240] for
> > >>> 8-bit chroma values. For 10-bit formats, the range 
> > >>> limits are
> > >>> multiplied by 4.
> > >>> "YCbCr to RGB: BT.709 full-swing":
> > >>> Only valid for YCbCr formats. CSC in accordance with 
> > >>> BT.709,
> > >>> but using the full range of each channel.
> > >>> "YCbCr to RGB: Use CTM":*
> > >>> Only valid for YCbCr formats. Use the matrix applied via 
> > >>> the
> > >>> plane's CTM property
> > >>> "RGB to RGB: Use CTM":*
> > >>> Only valid for RGB formats. Use the matrix applied via the
> > >>> plane's CTM property
> > >>> "Use CTM":*
> > >>> Valid for any format. Use the matrix applied via the 
> > >>> plane's
> > >>> CTM property
> > >>> ... any other values for BT.601, BT.2020, RGB to YCbCr etc. 
> > >>> etc. as
> > >>> they are required.
> > >> Having some RGB2RGB and YCBCR2RGB things in the same property 
> > >> seems
> > >> weird. I would just go with something very simple like:
> > >>
> > >> YCBCR_TO_RGB_CSC:
> > >> * BT.601
> > >> * BT.709
> > >> * custom matrix
> > >>
> > > I think we've agreed in #dri-devel that this CSC property
> > > can't/shouldn't be mapped on-to the existing (hardware 
> > > implementing
> > > the) CTM property - even in the case of per-plane color 
> > > management -
> > > because CSC needs to be done before DEGAMMA.
> > >
> > > So, I'm in favour of going with what you suggested in the 
> > > first place:
> > >
> > > A new YCBCR_TO_RGB_CSC property, enum type, with a list of fixed
> > > conversions. I'd drop the custom matrix for now, as we'd need 
> > > to add
> > > another property to attach the custom matrix blob too.
> > >
> > > I still think we need a way to specify 

Re: DRM Atomic property for color-space conversion

[Local user for Liviu Dudau]

On Thu, Mar 16, 2017 at 07:36:56PM +0200, Ville Syrjälä wrote:
> On Thu, Mar 16, 2017 at 07:05:12PM +0200, Sharma, Shashank wrote:
> > Regards
> > 
> > Shashank
> > 
> > 
> > On 3/16/2017 5:55 PM, Brian Starkey wrote:
> > > Hi,
> > >
> > > On Thu, Mar 16, 2017 at 05:14:07PM +0200, Sharma Shashank wrote:
> > >> Regards
> > >>
> > >> Shashank
> > >>
> > >>
> > >> On 3/16/2017 4:37 PM, Local user for Liviu Dudau wrote:
> > >>> On Thu, Mar 16, 2017 at 04:30:59PM +0200, Ville Syrjälä wrote:
> >  On Thu, Mar 16, 2017 at 04:20:29PM +0200, Sharma, Shashank wrote:
> > > Regards
> > >
> > > Shashank
> > >
> > >
> > > On 3/16/2017 4:07 PM, Ville Syrjälä wrote:
> > >> On Tue, Jan 31, 2017 at 03:55:41PM +, Brian Starkey wrote:
> > >>> On Tue, Jan 31, 2017 at 05:15:46PM +0200, Ville Syrjälä wrote:
> >  On Tue, Jan 31, 2017 at 12:33:29PM +, Brian Starkey wrote:
> > > Hi,
> > >
> > > On Mon, Jan 30, 2017 at 03:35:13PM +0200, Ville Syrjälä wrote:
> > >> On Fri, Jan 27, 2017 at 05:23:24PM +, Brian Starkey wrote:
> > >>> Hi,
> > >>>
> > >>> We're looking to enable the per-plane color management 
> > >>> hardware in
> > >>> Mali-DP with atomic properties, which has sparked some 
> > >>> conversation
> > >>> around how to handle YCbCr formats.
> > >>>
> > >>> As it stands today, it's assumed that a driver will 
> > >>> implicitly "do the
> > >>> right thing" to display a YCbCr buffer.
> > >>>
> > >>> YCbCr data often uses different gamma curves and signal 
> > >>> ranges (e.g.
> > >>> BT.609, BT.701, BT.2020, studio range, full-range), so its 
> > >>> desirable
> > >>> to be able to explicitly control the YCbCr to RGB conversion 
> > >>> process
> > >>> from userspace.
> > >>>
> > >>> We're proposing adding a "CSC" (color-space conversion) 
> > >>> property to
> > >>> control this - primarily per-plane for framebuffer->pipeline 
> > >>> CSC, but
> > >>> perhaps one per CRTC too for devices which have an RGB 
> > >>> pipeline and
> > >>> want to output in YUV to the display:
> > >>>
> > >>> Name: "CSC"
> > >>> Type: ENUM | ATOMIC;
> > >>> Enum values (representative):
> > >>> "default":
> > >>> Same behaviour as now. "Some kind" of YCbCr->RGB conversion
> > >>> for YCbCr buffers, bypass for RGB buffers
> > >>> "disable":
> > >>> Explicitly disable all colorspace conversion (i.e. use an
> > >>> identity matrix).
> > >>> "YCbCr to RGB: BT.709":
> > >>> Only valid for YCbCr formats. CSC in accordance with BT.709
> > >>> using [16..235] for (8-bit) luma values, and [16..240] for
> > >>> 8-bit chroma values. For 10-bit formats, the range 
> > >>> limits are
> > >>> multiplied by 4.
> > >>> "YCbCr to RGB: BT.709 full-swing":
> > >>> Only valid for YCbCr formats. CSC in accordance with 
> > >>> BT.709,
> > >>> but using the full range of each channel.
> > >>> "YCbCr to RGB: Use CTM":*
> > >>> Only valid for YCbCr formats. Use the matrix applied via 
> > >>> the
> > >>> plane's CTM property
> > >>> "RGB to RGB: Use CTM":*
> > >>> Only valid for RGB formats. Use the matrix applied via the
> > >>> plane's CTM property
> > >>> "Use CTM":*
> > >>> Valid for any format. Use the matrix applied via the 
> > >>> plane's
> > >>> CTM property
> > >>> ... any other values for BT.601, BT.2020, RGB to YCbCr etc. 
> > >>> etc. as
> > >>> they are required.
> > >> Having some RGB2RGB and YCBCR2RGB things in the same property 
> > >> seems
> > >> weird. I would just go with something very simple like:
> > >>
> > >> YCBCR_TO_RGB_CSC:
> > >> * BT.601
> > >> * BT.709
> > >> * custom matrix
> > >>
> > > I think we've agreed in #dri-devel that this CSC property
> > > can't/shouldn't be mapped on-to the existing (hardware 
> > > implementing
> > > the) CTM property - even in the case of per-plane color 
> > > management -
> > > because CSC needs to be done before DEGAMMA.
> > >
> > > So, I'm in favour of going with what you suggested in the 
> > > first place:
> > >
> > > A new YCBCR_TO_RGB_CSC property, enum type, with a list of fixed
> > > conversions. I'd drop the custom matrix for now, as we'd need 
> > > to add
> > > another property to attach the custom matrix blob too.
> > >
> > > I still think we need a way to specify 

Re: DRM Atomic property for color-space conversion

[Ville Syrjälä]

On Thu, Mar 16, 2017 at 07:05:12PM +0200, Sharma, Shashank wrote:
> Regards
> 
> Shashank
> 
> 
> On 3/16/2017 5:55 PM, Brian Starkey wrote:
> > Hi,
> >
> > On Thu, Mar 16, 2017 at 05:14:07PM +0200, Sharma Shashank wrote:
> >> Regards
> >>
> >> Shashank
> >>
> >>
> >> On 3/16/2017 4:37 PM, Local user for Liviu Dudau wrote:
> >>> On Thu, Mar 16, 2017 at 04:30:59PM +0200, Ville Syrjälä wrote:
>  On Thu, Mar 16, 2017 at 04:20:29PM +0200, Sharma, Shashank wrote:
> > Regards
> >
> > Shashank
> >
> >
> > On 3/16/2017 4:07 PM, Ville Syrjälä wrote:
> >> On Tue, Jan 31, 2017 at 03:55:41PM +, Brian Starkey wrote:
> >>> On Tue, Jan 31, 2017 at 05:15:46PM +0200, Ville Syrjälä wrote:
>  On Tue, Jan 31, 2017 at 12:33:29PM +, Brian Starkey wrote:
> > Hi,
> >
> > On Mon, Jan 30, 2017 at 03:35:13PM +0200, Ville Syrjälä wrote:
> >> On Fri, Jan 27, 2017 at 05:23:24PM +, Brian Starkey wrote:
> >>> Hi,
> >>>
> >>> We're looking to enable the per-plane color management 
> >>> hardware in
> >>> Mali-DP with atomic properties, which has sparked some 
> >>> conversation
> >>> around how to handle YCbCr formats.
> >>>
> >>> As it stands today, it's assumed that a driver will 
> >>> implicitly "do the
> >>> right thing" to display a YCbCr buffer.
> >>>
> >>> YCbCr data often uses different gamma curves and signal 
> >>> ranges (e.g.
> >>> BT.609, BT.701, BT.2020, studio range, full-range), so its 
> >>> desirable
> >>> to be able to explicitly control the YCbCr to RGB conversion 
> >>> process
> >>> from userspace.
> >>>
> >>> We're proposing adding a "CSC" (color-space conversion) 
> >>> property to
> >>> control this - primarily per-plane for framebuffer->pipeline 
> >>> CSC, but
> >>> perhaps one per CRTC too for devices which have an RGB 
> >>> pipeline and
> >>> want to output in YUV to the display:
> >>>
> >>> Name: "CSC"
> >>> Type: ENUM | ATOMIC;
> >>> Enum values (representative):
> >>> "default":
> >>> Same behaviour as now. "Some kind" of YCbCr->RGB conversion
> >>> for YCbCr buffers, bypass for RGB buffers
> >>> "disable":
> >>> Explicitly disable all colorspace conversion (i.e. use an
> >>> identity matrix).
> >>> "YCbCr to RGB: BT.709":
> >>> Only valid for YCbCr formats. CSC in accordance with BT.709
> >>> using [16..235] for (8-bit) luma values, and [16..240] for
> >>> 8-bit chroma values. For 10-bit formats, the range 
> >>> limits are
> >>> multiplied by 4.
> >>> "YCbCr to RGB: BT.709 full-swing":
> >>> Only valid for YCbCr formats. CSC in accordance with 
> >>> BT.709,
> >>> but using the full range of each channel.
> >>> "YCbCr to RGB: Use CTM":*
> >>> Only valid for YCbCr formats. Use the matrix applied via 
> >>> the
> >>> plane's CTM property
> >>> "RGB to RGB: Use CTM":*
> >>> Only valid for RGB formats. Use the matrix applied via the
> >>> plane's CTM property
> >>> "Use CTM":*
> >>> Valid for any format. Use the matrix applied via the 
> >>> plane's
> >>> CTM property
> >>> ... any other values for BT.601, BT.2020, RGB to YCbCr etc. 
> >>> etc. as
> >>> they are required.
> >> Having some RGB2RGB and YCBCR2RGB things in the same property 
> >> seems
> >> weird. I would just go with something very simple like:
> >>
> >> YCBCR_TO_RGB_CSC:
> >> * BT.601
> >> * BT.709
> >> * custom matrix
> >>
> > I think we've agreed in #dri-devel that this CSC property
> > can't/shouldn't be mapped on-to the existing (hardware 
> > implementing
> > the) CTM property - even in the case of per-plane color 
> > management -
> > because CSC needs to be done before DEGAMMA.
> >
> > So, I'm in favour of going with what you suggested in the 
> > first place:
> >
> > A new YCBCR_TO_RGB_CSC property, enum type, with a list of fixed
> > conversions. I'd drop the custom matrix for now, as we'd need 
> > to add
> > another property to attach the custom matrix blob too.
> >
> > I still think we need a way to specify whether the source data 
> > range
> > is broadcast/full-range, so perhaps the enum list should be 
> > expanded
> > to all combinations of BT.601/BT.709 + broadcast/full-range.
>  Sounds reasonable. Not that much full range YCbCr stuff out there
>  

Re: DRM Atomic property for color-space conversion

[Ville Syrjälä]

On Thu, Mar 16, 2017 at 07:05:12PM +0200, Sharma, Shashank wrote:
> Regards
> 
> Shashank
> 
> 
> On 3/16/2017 5:55 PM, Brian Starkey wrote:
> > Hi,
> >
> > On Thu, Mar 16, 2017 at 05:14:07PM +0200, Sharma Shashank wrote:
> >> Regards
> >>
> >> Shashank
> >>
> >>
> >> On 3/16/2017 4:37 PM, Local user for Liviu Dudau wrote:
> >>> On Thu, Mar 16, 2017 at 04:30:59PM +0200, Ville Syrjälä wrote:
>  On Thu, Mar 16, 2017 at 04:20:29PM +0200, Sharma, Shashank wrote:
> > Regards
> >
> > Shashank
> >
> >
> > On 3/16/2017 4:07 PM, Ville Syrjälä wrote:
> >> On Tue, Jan 31, 2017 at 03:55:41PM +, Brian Starkey wrote:
> >>> On Tue, Jan 31, 2017 at 05:15:46PM +0200, Ville Syrjälä wrote:
>  On Tue, Jan 31, 2017 at 12:33:29PM +, Brian Starkey wrote:
> > Hi,
> >
> > On Mon, Jan 30, 2017 at 03:35:13PM +0200, Ville Syrjälä wrote:
> >> On Fri, Jan 27, 2017 at 05:23:24PM +, Brian Starkey wrote:
> >>> Hi,
> >>>
> >>> We're looking to enable the per-plane color management 
> >>> hardware in
> >>> Mali-DP with atomic properties, which has sparked some 
> >>> conversation
> >>> around how to handle YCbCr formats.
> >>>
> >>> As it stands today, it's assumed that a driver will 
> >>> implicitly "do the
> >>> right thing" to display a YCbCr buffer.
> >>>
> >>> YCbCr data often uses different gamma curves and signal 
> >>> ranges (e.g.
> >>> BT.609, BT.701, BT.2020, studio range, full-range), so its 
> >>> desirable
> >>> to be able to explicitly control the YCbCr to RGB conversion 
> >>> process
> >>> from userspace.
> >>>
> >>> We're proposing adding a "CSC" (color-space conversion) 
> >>> property to
> >>> control this - primarily per-plane for framebuffer->pipeline 
> >>> CSC, but
> >>> perhaps one per CRTC too for devices which have an RGB 
> >>> pipeline and
> >>> want to output in YUV to the display:
> >>>
> >>> Name: "CSC"
> >>> Type: ENUM | ATOMIC;
> >>> Enum values (representative):
> >>> "default":
> >>> Same behaviour as now. "Some kind" of YCbCr->RGB conversion
> >>> for YCbCr buffers, bypass for RGB buffers
> >>> "disable":
> >>> Explicitly disable all colorspace conversion (i.e. use an
> >>> identity matrix).
> >>> "YCbCr to RGB: BT.709":
> >>> Only valid for YCbCr formats. CSC in accordance with BT.709
> >>> using [16..235] for (8-bit) luma values, and [16..240] for
> >>> 8-bit chroma values. For 10-bit formats, the range 
> >>> limits are
> >>> multiplied by 4.
> >>> "YCbCr to RGB: BT.709 full-swing":
> >>> Only valid for YCbCr formats. CSC in accordance with 
> >>> BT.709,
> >>> but using the full range of each channel.
> >>> "YCbCr to RGB: Use CTM":*
> >>> Only valid for YCbCr formats. Use the matrix applied via 
> >>> the
> >>> plane's CTM property
> >>> "RGB to RGB: Use CTM":*
> >>> Only valid for RGB formats. Use the matrix applied via the
> >>> plane's CTM property
> >>> "Use CTM":*
> >>> Valid for any format. Use the matrix applied via the 
> >>> plane's
> >>> CTM property
> >>> ... any other values for BT.601, BT.2020, RGB to YCbCr etc. 
> >>> etc. as
> >>> they are required.
> >> Having some RGB2RGB and YCBCR2RGB things in the same property 
> >> seems
> >> weird. I would just go with something very simple like:
> >>
> >> YCBCR_TO_RGB_CSC:
> >> * BT.601
> >> * BT.709
> >> * custom matrix
> >>
> > I think we've agreed in #dri-devel that this CSC property
> > can't/shouldn't be mapped on-to the existing (hardware 
> > implementing
> > the) CTM property - even in the case of per-plane color 
> > management -
> > because CSC needs to be done before DEGAMMA.
> >
> > So, I'm in favour of going with what you suggested in the 
> > first place:
> >
> > A new YCBCR_TO_RGB_CSC property, enum type, with a list of fixed
> > conversions. I'd drop the custom matrix for now, as we'd need 
> > to add
> > another property to attach the custom matrix blob too.
> >
> > I still think we need a way to specify whether the source data 
> > range
> > is broadcast/full-range, so perhaps the enum list should be 
> > expanded
> > to all combinations of BT.601/BT.709 + broadcast/full-range.
>  Sounds reasonable. Not that much full range YCbCr stuff out there
>  

Re: DRM Atomic property for color-space conversion

[Sharma, Shashank]

Regards

Shashank


On 3/16/2017 5:55 PM, Brian Starkey wrote:

Hi,

On Thu, Mar 16, 2017 at 05:14:07PM +0200, Sharma Shashank wrote:

Regards

Shashank


On 3/16/2017 4:37 PM, Local user for Liviu Dudau wrote:

On Thu, Mar 16, 2017 at 04:30:59PM +0200, Ville Syrjälä wrote:

On Thu, Mar 16, 2017 at 04:20:29PM +0200, Sharma, Shashank wrote:

Regards

Shashank


On 3/16/2017 4:07 PM, Ville Syrjälä wrote:

On Tue, Jan 31, 2017 at 03:55:41PM +, Brian Starkey wrote:

On Tue, Jan 31, 2017 at 05:15:46PM +0200, Ville Syrjälä wrote:

On Tue, Jan 31, 2017 at 12:33:29PM +, Brian Starkey wrote:

Hi,

On Mon, Jan 30, 2017 at 03:35:13PM +0200, Ville Syrjälä wrote:

On Fri, Jan 27, 2017 at 05:23:24PM +, Brian Starkey wrote:

Hi,

We're looking to enable the per-plane color management 
hardware in
Mali-DP with atomic properties, which has sparked some 
conversation

around how to handle YCbCr formats.

As it stands today, it's assumed that a driver will 
implicitly "do the

right thing" to display a YCbCr buffer.

YCbCr data often uses different gamma curves and signal 
ranges (e.g.
BT.609, BT.701, BT.2020, studio range, full-range), so its 
desirable
to be able to explicitly control the YCbCr to RGB conversion 
process

from userspace.

We're proposing adding a "CSC" (color-space conversion) 
property to
control this - primarily per-plane for framebuffer->pipeline 
CSC, but
perhaps one per CRTC too for devices which have an RGB 
pipeline and

want to output in YUV to the display:

Name: "CSC"
Type: ENUM | ATOMIC;
Enum values (representative):
"default":
Same behaviour as now. "Some kind" of YCbCr->RGB conversion
for YCbCr buffers, bypass for RGB buffers
"disable":
Explicitly disable all colorspace conversion (i.e. use an
identity matrix).
"YCbCr to RGB: BT.709":
Only valid for YCbCr formats. CSC in accordance with BT.709
using [16..235] for (8-bit) luma values, and [16..240] for
8-bit chroma values. For 10-bit formats, the range 
limits are

multiplied by 4.
"YCbCr to RGB: BT.709 full-swing":
Only valid for YCbCr formats. CSC in accordance with 
BT.709,

but using the full range of each channel.
"YCbCr to RGB: Use CTM":*
Only valid for YCbCr formats. Use the matrix applied via 
the

plane's CTM property
"RGB to RGB: Use CTM":*
Only valid for RGB formats. Use the matrix applied via the
plane's CTM property
"Use CTM":*
Valid for any format. Use the matrix applied via the 
plane's

CTM property
... any other values for BT.601, BT.2020, RGB to YCbCr etc. 
etc. as

they are required.
Having some RGB2RGB and YCBCR2RGB things in the same property 
seems

weird. I would just go with something very simple like:

YCBCR_TO_RGB_CSC:
* BT.601
* BT.709
* custom matrix


I think we've agreed in #dri-devel that this CSC property
can't/shouldn't be mapped on-to the existing (hardware 
implementing
the) CTM property - even in the case of per-plane color 
management -

because CSC needs to be done before DEGAMMA.

So, I'm in favour of going with what you suggested in the 
first place:


A new YCBCR_TO_RGB_CSC property, enum type, with a list of fixed
conversions. I'd drop the custom matrix for now, as we'd need 
to add

another property to attach the custom matrix blob too.

I still think we need a way to specify whether the source data 
range
is broadcast/full-range, so perhaps the enum list should be 
expanded

to all combinations of BT.601/BT.709 + broadcast/full-range.

Sounds reasonable. Not that much full range YCbCr stuff out there
perhaps. Well, apart from jpegs I suppose. But no harm in being 
able

to deal with it.

(I'm not sure what the canonical naming for 
broadcast/full-range is,

we call them narrow and wide)

We tend to call them full vs. limited range. That's how our
"Broadcast RGB" property is defined as well.


OK, using the same ones sounds sensible.

And trying to use the same thing for the crtc stuff is 
probably not

going to end well. Like Daniel said we already have the
'Broadcast RGB' property muddying the waters there, and that 
stuff

also ties in with what colorspace we signal to the sink via
infoframes/whatever the DP thing was called. So my gut 
feeling is

that trying to use the same property everywhere will just end up
messy.
Yeah, agreed. If/when someone wants to add CSC on the output 
of a CRTC

(after GAMMA), we can add a new property.

That makes me wonder about calling this one 
SOURCE_YCBCR_TO_RGB_CSC to
be explicit that it describes the source data. Then we can 
later add

SINK_RGB_TO_YCBCR_CSC, and it will be reasonably obvious that its
value describes the output data rather than the input data.
Source and sink have a slight connotation in my mind wrt. the 
box that
produces the display signal and the box that eats the signal. 
So trying
to use the same terms to describe the internals of the pipeline 
inside
the "source box" migth lead to some confusion. But we do 
probably need
some decent names for these to make the 

Re: DRM Atomic property for color-space conversion

[Sharma, Shashank]

Regards

Shashank


On 3/16/2017 5:55 PM, Brian Starkey wrote:

Hi,

On Thu, Mar 16, 2017 at 05:14:07PM +0200, Sharma Shashank wrote:

Regards

Shashank


On 3/16/2017 4:37 PM, Local user for Liviu Dudau wrote:

On Thu, Mar 16, 2017 at 04:30:59PM +0200, Ville Syrjälä wrote:

On Thu, Mar 16, 2017 at 04:20:29PM +0200, Sharma, Shashank wrote:

Regards

Shashank


On 3/16/2017 4:07 PM, Ville Syrjälä wrote:

On Tue, Jan 31, 2017 at 03:55:41PM +, Brian Starkey wrote:

On Tue, Jan 31, 2017 at 05:15:46PM +0200, Ville Syrjälä wrote:

On Tue, Jan 31, 2017 at 12:33:29PM +, Brian Starkey wrote:

Hi,

On Mon, Jan 30, 2017 at 03:35:13PM +0200, Ville Syrjälä wrote:

On Fri, Jan 27, 2017 at 05:23:24PM +, Brian Starkey wrote:

Hi,

We're looking to enable the per-plane color management 
hardware in
Mali-DP with atomic properties, which has sparked some 
conversation

around how to handle YCbCr formats.

As it stands today, it's assumed that a driver will 
implicitly "do the

right thing" to display a YCbCr buffer.

YCbCr data often uses different gamma curves and signal 
ranges (e.g.
BT.609, BT.701, BT.2020, studio range, full-range), so its 
desirable
to be able to explicitly control the YCbCr to RGB conversion 
process

from userspace.

We're proposing adding a "CSC" (color-space conversion) 
property to
control this - primarily per-plane for framebuffer->pipeline 
CSC, but
perhaps one per CRTC too for devices which have an RGB 
pipeline and

want to output in YUV to the display:

Name: "CSC"
Type: ENUM | ATOMIC;
Enum values (representative):
"default":
Same behaviour as now. "Some kind" of YCbCr->RGB conversion
for YCbCr buffers, bypass for RGB buffers
"disable":
Explicitly disable all colorspace conversion (i.e. use an
identity matrix).
"YCbCr to RGB: BT.709":
Only valid for YCbCr formats. CSC in accordance with BT.709
using [16..235] for (8-bit) luma values, and [16..240] for
8-bit chroma values. For 10-bit formats, the range 
limits are

multiplied by 4.
"YCbCr to RGB: BT.709 full-swing":
Only valid for YCbCr formats. CSC in accordance with 
BT.709,

but using the full range of each channel.
"YCbCr to RGB: Use CTM":*
Only valid for YCbCr formats. Use the matrix applied via 
the

plane's CTM property
"RGB to RGB: Use CTM":*
Only valid for RGB formats. Use the matrix applied via the
plane's CTM property
"Use CTM":*
Valid for any format. Use the matrix applied via the 
plane's

CTM property
... any other values for BT.601, BT.2020, RGB to YCbCr etc. 
etc. as

they are required.
Having some RGB2RGB and YCBCR2RGB things in the same property 
seems

weird. I would just go with something very simple like:

YCBCR_TO_RGB_CSC:
* BT.601
* BT.709
* custom matrix


I think we've agreed in #dri-devel that this CSC property
can't/shouldn't be mapped on-to the existing (hardware 
implementing
the) CTM property - even in the case of per-plane color 
management -

because CSC needs to be done before DEGAMMA.

So, I'm in favour of going with what you suggested in the 
first place:


A new YCBCR_TO_RGB_CSC property, enum type, with a list of fixed
conversions. I'd drop the custom matrix for now, as we'd need 
to add

another property to attach the custom matrix blob too.

I still think we need a way to specify whether the source data 
range
is broadcast/full-range, so perhaps the enum list should be 
expanded

to all combinations of BT.601/BT.709 + broadcast/full-range.

Sounds reasonable. Not that much full range YCbCr stuff out there
perhaps. Well, apart from jpegs I suppose. But no harm in being 
able

to deal with it.

(I'm not sure what the canonical naming for 
broadcast/full-range is,

we call them narrow and wide)

We tend to call them full vs. limited range. That's how our
"Broadcast RGB" property is defined as well.


OK, using the same ones sounds sensible.

And trying to use the same thing for the crtc stuff is 
probably not

going to end well. Like Daniel said we already have the
'Broadcast RGB' property muddying the waters there, and that 
stuff

also ties in with what colorspace we signal to the sink via
infoframes/whatever the DP thing was called. So my gut 
feeling is

that trying to use the same property everywhere will just end up
messy.
Yeah, agreed. If/when someone wants to add CSC on the output 
of a CRTC

(after GAMMA), we can add a new property.

That makes me wonder about calling this one 
SOURCE_YCBCR_TO_RGB_CSC to
be explicit that it describes the source data. Then we can 
later add

SINK_RGB_TO_YCBCR_CSC, and it will be reasonably obvious that its
value describes the output data rather than the input data.
Source and sink have a slight connotation in my mind wrt. the 
box that
produces the display signal and the box that eats the signal. 
So trying
to use the same terms to describe the internals of the pipeline 
inside
the "source box" migth lead to some confusion. But we do 
probably need
some decent names for these to make the 

Re: DRM Atomic property for color-space conversion

[Brian Starkey]

Hi,

On Thu, Mar 16, 2017 at 05:14:07PM +0200, Sharma Shashank wrote:

Regards

Shashank


On 3/16/2017 4:37 PM, Local user for Liviu Dudau wrote:

On Thu, Mar 16, 2017 at 04:30:59PM +0200, Ville Syrjälä wrote:

On Thu, Mar 16, 2017 at 04:20:29PM +0200, Sharma, Shashank wrote:

Regards

Shashank


On 3/16/2017 4:07 PM, Ville Syrjälä wrote:

On Tue, Jan 31, 2017 at 03:55:41PM +, Brian Starkey wrote:

On Tue, Jan 31, 2017 at 05:15:46PM +0200, Ville Syrjälä wrote:

On Tue, Jan 31, 2017 at 12:33:29PM +, Brian Starkey wrote:

Hi,

On Mon, Jan 30, 2017 at 03:35:13PM +0200, Ville Syrjälä wrote:

On Fri, Jan 27, 2017 at 05:23:24PM +, Brian Starkey wrote:

Hi,

We're looking to enable the per-plane color management hardware in
Mali-DP with atomic properties, which has sparked some conversation
around how to handle YCbCr formats.

As it stands today, it's assumed that a driver will implicitly "do the
right thing" to display a YCbCr buffer.

YCbCr data often uses different gamma curves and signal ranges (e.g.
BT.609, BT.701, BT.2020, studio range, full-range), so its desirable
to be able to explicitly control the YCbCr to RGB conversion process
from userspace.

We're proposing adding a "CSC" (color-space conversion) property to
control this - primarily per-plane for framebuffer->pipeline CSC, but
perhaps one per CRTC too for devices which have an RGB pipeline and
want to output in YUV to the display:

Name: "CSC"
Type: ENUM | ATOMIC;
Enum values (representative):
"default":
Same behaviour as now. "Some kind" of YCbCr->RGB conversion
for YCbCr buffers, bypass for RGB buffers
"disable":
Explicitly disable all colorspace conversion (i.e. use an
identity matrix).
"YCbCr to RGB: BT.709":
Only valid for YCbCr formats. CSC in accordance with BT.709
using [16..235] for (8-bit) luma values, and [16..240] for
8-bit chroma values. For 10-bit formats, the range limits are
multiplied by 4.
"YCbCr to RGB: BT.709 full-swing":
Only valid for YCbCr formats. CSC in accordance with BT.709,
but using the full range of each channel.
"YCbCr to RGB: Use CTM":*
Only valid for YCbCr formats. Use the matrix applied via the
plane's CTM property
"RGB to RGB: Use CTM":*
Only valid for RGB formats. Use the matrix applied via the
plane's CTM property
"Use CTM":*
Valid for any format. Use the matrix applied via the plane's
CTM property
... any other values for BT.601, BT.2020, RGB to YCbCr etc. etc. as
they are required.

Having some RGB2RGB and YCBCR2RGB things in the same property seems
weird. I would just go with something very simple like:

YCBCR_TO_RGB_CSC:
* BT.601
* BT.709
* custom matrix


I think we've agreed in #dri-devel that this CSC property
can't/shouldn't be mapped on-to the existing (hardware implementing
the) CTM property - even in the case of per-plane color management -
because CSC needs to be done before DEGAMMA.

So, I'm in favour of going with what you suggested in the first place:

A new YCBCR_TO_RGB_CSC property, enum type, with a list of fixed
conversions. I'd drop the custom matrix for now, as we'd need to add
another property to attach the custom matrix blob too.

I still think we need a way to specify whether the source data range
is broadcast/full-range, so perhaps the enum list should be expanded
to all combinations of BT.601/BT.709 + broadcast/full-range.

Sounds reasonable. Not that much full range YCbCr stuff out there
perhaps. Well, apart from jpegs I suppose. But no harm in being able
to deal with it.


(I'm not sure what the canonical naming for broadcast/full-range is,
we call them narrow and wide)

We tend to call them full vs. limited range. That's how our
"Broadcast RGB" property is defined as well.


OK, using the same ones sounds sensible.


And trying to use the same thing for the crtc stuff is probably not
going to end well. Like Daniel said we already have the
'Broadcast RGB' property muddying the waters there, and that stuff
also ties in with what colorspace we signal to the sink via
infoframes/whatever the DP thing was called. So my gut feeling is
that trying to use the same property everywhere will just end up
messy.

Yeah, agreed. If/when someone wants to add CSC on the output of a CRTC
(after GAMMA), we can add a new property.

That makes me wonder about calling this one SOURCE_YCBCR_TO_RGB_CSC to
be explicit that it describes the source data. Then we can later add
SINK_RGB_TO_YCBCR_CSC, and it will be reasonably obvious that its
value describes the output data rather than the input data.

Source and sink have a slight connotation in my mind wrt. the box that
produces the display signal and the box that eats the signal. So trying
to use the same terms to describe the internals of the pipeline inside
the "source box" migth lead to some confusion. But we do probably need
some decent names for these to make the layout of the pipeline clear.
Input/output are the 

Re: DRM Atomic property for color-space conversion

[Brian Starkey]

Hi,

On Thu, Mar 16, 2017 at 05:14:07PM +0200, Sharma Shashank wrote:

Regards

Shashank


On 3/16/2017 4:37 PM, Local user for Liviu Dudau wrote:

On Thu, Mar 16, 2017 at 04:30:59PM +0200, Ville Syrjälä wrote:

On Thu, Mar 16, 2017 at 04:20:29PM +0200, Sharma, Shashank wrote:

Regards

Shashank


On 3/16/2017 4:07 PM, Ville Syrjälä wrote:

On Tue, Jan 31, 2017 at 03:55:41PM +, Brian Starkey wrote:

On Tue, Jan 31, 2017 at 05:15:46PM +0200, Ville Syrjälä wrote:

On Tue, Jan 31, 2017 at 12:33:29PM +, Brian Starkey wrote:

Hi,

On Mon, Jan 30, 2017 at 03:35:13PM +0200, Ville Syrjälä wrote:

On Fri, Jan 27, 2017 at 05:23:24PM +, Brian Starkey wrote:

Hi,

We're looking to enable the per-plane color management hardware in
Mali-DP with atomic properties, which has sparked some conversation
around how to handle YCbCr formats.

As it stands today, it's assumed that a driver will implicitly "do the
right thing" to display a YCbCr buffer.

YCbCr data often uses different gamma curves and signal ranges (e.g.
BT.609, BT.701, BT.2020, studio range, full-range), so its desirable
to be able to explicitly control the YCbCr to RGB conversion process
from userspace.

We're proposing adding a "CSC" (color-space conversion) property to
control this - primarily per-plane for framebuffer->pipeline CSC, but
perhaps one per CRTC too for devices which have an RGB pipeline and
want to output in YUV to the display:

Name: "CSC"
Type: ENUM | ATOMIC;
Enum values (representative):
"default":
Same behaviour as now. "Some kind" of YCbCr->RGB conversion
for YCbCr buffers, bypass for RGB buffers
"disable":
Explicitly disable all colorspace conversion (i.e. use an
identity matrix).
"YCbCr to RGB: BT.709":
Only valid for YCbCr formats. CSC in accordance with BT.709
using [16..235] for (8-bit) luma values, and [16..240] for
8-bit chroma values. For 10-bit formats, the range limits are
multiplied by 4.
"YCbCr to RGB: BT.709 full-swing":
Only valid for YCbCr formats. CSC in accordance with BT.709,
but using the full range of each channel.
"YCbCr to RGB: Use CTM":*
Only valid for YCbCr formats. Use the matrix applied via the
plane's CTM property
"RGB to RGB: Use CTM":*
Only valid for RGB formats. Use the matrix applied via the
plane's CTM property
"Use CTM":*
Valid for any format. Use the matrix applied via the plane's
CTM property
... any other values for BT.601, BT.2020, RGB to YCbCr etc. etc. as
they are required.

Having some RGB2RGB and YCBCR2RGB things in the same property seems
weird. I would just go with something very simple like:

YCBCR_TO_RGB_CSC:
* BT.601
* BT.709
* custom matrix


I think we've agreed in #dri-devel that this CSC property
can't/shouldn't be mapped on-to the existing (hardware implementing
the) CTM property - even in the case of per-plane color management -
because CSC needs to be done before DEGAMMA.

So, I'm in favour of going with what you suggested in the first place:

A new YCBCR_TO_RGB_CSC property, enum type, with a list of fixed
conversions. I'd drop the custom matrix for now, as we'd need to add
another property to attach the custom matrix blob too.

I still think we need a way to specify whether the source data range
is broadcast/full-range, so perhaps the enum list should be expanded
to all combinations of BT.601/BT.709 + broadcast/full-range.

Sounds reasonable. Not that much full range YCbCr stuff out there
perhaps. Well, apart from jpegs I suppose. But no harm in being able
to deal with it.


(I'm not sure what the canonical naming for broadcast/full-range is,
we call them narrow and wide)

We tend to call them full vs. limited range. That's how our
"Broadcast RGB" property is defined as well.


OK, using the same ones sounds sensible.


And trying to use the same thing for the crtc stuff is probably not
going to end well. Like Daniel said we already have the
'Broadcast RGB' property muddying the waters there, and that stuff
also ties in with what colorspace we signal to the sink via
infoframes/whatever the DP thing was called. So my gut feeling is
that trying to use the same property everywhere will just end up
messy.

Yeah, agreed. If/when someone wants to add CSC on the output of a CRTC
(after GAMMA), we can add a new property.

That makes me wonder about calling this one SOURCE_YCBCR_TO_RGB_CSC to
be explicit that it describes the source data. Then we can later add
SINK_RGB_TO_YCBCR_CSC, and it will be reasonably obvious that its
value describes the output data rather than the input data.

Source and sink have a slight connotation in my mind wrt. the box that
produces the display signal and the box that eats the signal. So trying
to use the same terms to describe the internals of the pipeline inside
the "source box" migth lead to some confusion. But we do probably need
some decent names for these to make the layout of the pipeline clear.
Input/output are the 

Re: DRM Atomic property for color-space conversion

[Sharma, Shashank]

Regards

Shashank


On 3/16/2017 4:37 PM, Local user for Liviu Dudau wrote:

On Thu, Mar 16, 2017 at 04:30:59PM +0200, Ville Syrjälä wrote:

On Thu, Mar 16, 2017 at 04:20:29PM +0200, Sharma, Shashank wrote:

Regards

Shashank


On 3/16/2017 4:07 PM, Ville Syrjälä wrote:

On Tue, Jan 31, 2017 at 03:55:41PM +, Brian Starkey wrote:

On Tue, Jan 31, 2017 at 05:15:46PM +0200, Ville Syrjälä wrote:

On Tue, Jan 31, 2017 at 12:33:29PM +, Brian Starkey wrote:

Hi,

On Mon, Jan 30, 2017 at 03:35:13PM +0200, Ville Syrjälä wrote:

On Fri, Jan 27, 2017 at 05:23:24PM +, Brian Starkey wrote:

Hi,

We're looking to enable the per-plane color management hardware in
Mali-DP with atomic properties, which has sparked some conversation
around how to handle YCbCr formats.

As it stands today, it's assumed that a driver will implicitly "do the
right thing" to display a YCbCr buffer.

YCbCr data often uses different gamma curves and signal ranges (e.g.
BT.609, BT.701, BT.2020, studio range, full-range), so its desirable
to be able to explicitly control the YCbCr to RGB conversion process
from userspace.

We're proposing adding a "CSC" (color-space conversion) property to
control this - primarily per-plane for framebuffer->pipeline CSC, but
perhaps one per CRTC too for devices which have an RGB pipeline and
want to output in YUV to the display:

Name: "CSC"
Type: ENUM | ATOMIC;
Enum values (representative):
"default":
Same behaviour as now. "Some kind" of YCbCr->RGB conversion
for YCbCr buffers, bypass for RGB buffers
"disable":
Explicitly disable all colorspace conversion (i.e. use an
identity matrix).
"YCbCr to RGB: BT.709":
Only valid for YCbCr formats. CSC in accordance with BT.709
using [16..235] for (8-bit) luma values, and [16..240] for
8-bit chroma values. For 10-bit formats, the range limits are
multiplied by 4.
"YCbCr to RGB: BT.709 full-swing":
Only valid for YCbCr formats. CSC in accordance with BT.709,
but using the full range of each channel.
"YCbCr to RGB: Use CTM":*
Only valid for YCbCr formats. Use the matrix applied via the
plane's CTM property
"RGB to RGB: Use CTM":*
Only valid for RGB formats. Use the matrix applied via the
plane's CTM property
"Use CTM":*
Valid for any format. Use the matrix applied via the plane's
CTM property
... any other values for BT.601, BT.2020, RGB to YCbCr etc. etc. as
they are required.

Having some RGB2RGB and YCBCR2RGB things in the same property seems
weird. I would just go with something very simple like:

YCBCR_TO_RGB_CSC:
* BT.601
* BT.709
* custom matrix


I think we've agreed in #dri-devel that this CSC property
can't/shouldn't be mapped on-to the existing (hardware implementing
the) CTM property - even in the case of per-plane color management -
because CSC needs to be done before DEGAMMA.

So, I'm in favour of going with what you suggested in the first place:

A new YCBCR_TO_RGB_CSC property, enum type, with a list of fixed
conversions. I'd drop the custom matrix for now, as we'd need to add
another property to attach the custom matrix blob too.

I still think we need a way to specify whether the source data range
is broadcast/full-range, so perhaps the enum list should be expanded
to all combinations of BT.601/BT.709 + broadcast/full-range.

Sounds reasonable. Not that much full range YCbCr stuff out there
perhaps. Well, apart from jpegs I suppose. But no harm in being able
to deal with it.


(I'm not sure what the canonical naming for broadcast/full-range is,
we call them narrow and wide)

We tend to call them full vs. limited range. That's how our
"Broadcast RGB" property is defined as well.


OK, using the same ones sounds sensible.


And trying to use the same thing for the crtc stuff is probably not
going to end well. Like Daniel said we already have the
'Broadcast RGB' property muddying the waters there, and that stuff
also ties in with what colorspace we signal to the sink via
infoframes/whatever the DP thing was called. So my gut feeling is
that trying to use the same property everywhere will just end up
messy.

Yeah, agreed. If/when someone wants to add CSC on the output of a CRTC
(after GAMMA), we can add a new property.

That makes me wonder about calling this one SOURCE_YCBCR_TO_RGB_CSC to
be explicit that it describes the source data. Then we can later add
SINK_RGB_TO_YCBCR_CSC, and it will be reasonably obvious that its
value describes the output data rather than the input data.

Source and sink have a slight connotation in my mind wrt. the box that
produces the display signal and the box that eats the signal. So trying
to use the same terms to describe the internals of the pipeline inside
the "source box" migth lead to some confusion. But we do probably need
some decent names for these to make the layout of the pipeline clear.
Input/output are the other names that popped to my mind but those aren't
necessarily any 

Re: DRM Atomic property for color-space conversion

[Sharma, Shashank]

Regards

Shashank


On 3/16/2017 4:37 PM, Local user for Liviu Dudau wrote:

On Thu, Mar 16, 2017 at 04:30:59PM +0200, Ville Syrjälä wrote:

On Thu, Mar 16, 2017 at 04:20:29PM +0200, Sharma, Shashank wrote:

Regards

Shashank


On 3/16/2017 4:07 PM, Ville Syrjälä wrote:

On Tue, Jan 31, 2017 at 03:55:41PM +, Brian Starkey wrote:

On Tue, Jan 31, 2017 at 05:15:46PM +0200, Ville Syrjälä wrote:

On Tue, Jan 31, 2017 at 12:33:29PM +, Brian Starkey wrote:

Hi,

On Mon, Jan 30, 2017 at 03:35:13PM +0200, Ville Syrjälä wrote:

On Fri, Jan 27, 2017 at 05:23:24PM +, Brian Starkey wrote:

Hi,

We're looking to enable the per-plane color management hardware in
Mali-DP with atomic properties, which has sparked some conversation
around how to handle YCbCr formats.

As it stands today, it's assumed that a driver will implicitly "do the
right thing" to display a YCbCr buffer.

YCbCr data often uses different gamma curves and signal ranges (e.g.
BT.609, BT.701, BT.2020, studio range, full-range), so its desirable
to be able to explicitly control the YCbCr to RGB conversion process
from userspace.

We're proposing adding a "CSC" (color-space conversion) property to
control this - primarily per-plane for framebuffer->pipeline CSC, but
perhaps one per CRTC too for devices which have an RGB pipeline and
want to output in YUV to the display:

Name: "CSC"
Type: ENUM | ATOMIC;
Enum values (representative):
"default":
Same behaviour as now. "Some kind" of YCbCr->RGB conversion
for YCbCr buffers, bypass for RGB buffers
"disable":
Explicitly disable all colorspace conversion (i.e. use an
identity matrix).
"YCbCr to RGB: BT.709":
Only valid for YCbCr formats. CSC in accordance with BT.709
using [16..235] for (8-bit) luma values, and [16..240] for
8-bit chroma values. For 10-bit formats, the range limits are
multiplied by 4.
"YCbCr to RGB: BT.709 full-swing":
Only valid for YCbCr formats. CSC in accordance with BT.709,
but using the full range of each channel.
"YCbCr to RGB: Use CTM":*
Only valid for YCbCr formats. Use the matrix applied via the
plane's CTM property
"RGB to RGB: Use CTM":*
Only valid for RGB formats. Use the matrix applied via the
plane's CTM property
"Use CTM":*
Valid for any format. Use the matrix applied via the plane's
CTM property
... any other values for BT.601, BT.2020, RGB to YCbCr etc. etc. as
they are required.

Having some RGB2RGB and YCBCR2RGB things in the same property seems
weird. I would just go with something very simple like:

YCBCR_TO_RGB_CSC:
* BT.601
* BT.709
* custom matrix


I think we've agreed in #dri-devel that this CSC property
can't/shouldn't be mapped on-to the existing (hardware implementing
the) CTM property - even in the case of per-plane color management -
because CSC needs to be done before DEGAMMA.

So, I'm in favour of going with what you suggested in the first place:

A new YCBCR_TO_RGB_CSC property, enum type, with a list of fixed
conversions. I'd drop the custom matrix for now, as we'd need to add
another property to attach the custom matrix blob too.

I still think we need a way to specify whether the source data range
is broadcast/full-range, so perhaps the enum list should be expanded
to all combinations of BT.601/BT.709 + broadcast/full-range.

Sounds reasonable. Not that much full range YCbCr stuff out there
perhaps. Well, apart from jpegs I suppose. But no harm in being able
to deal with it.


(I'm not sure what the canonical naming for broadcast/full-range is,
we call them narrow and wide)

We tend to call them full vs. limited range. That's how our
"Broadcast RGB" property is defined as well.


OK, using the same ones sounds sensible.


And trying to use the same thing for the crtc stuff is probably not
going to end well. Like Daniel said we already have the
'Broadcast RGB' property muddying the waters there, and that stuff
also ties in with what colorspace we signal to the sink via
infoframes/whatever the DP thing was called. So my gut feeling is
that trying to use the same property everywhere will just end up
messy.

Yeah, agreed. If/when someone wants to add CSC on the output of a CRTC
(after GAMMA), we can add a new property.

That makes me wonder about calling this one SOURCE_YCBCR_TO_RGB_CSC to
be explicit that it describes the source data. Then we can later add
SINK_RGB_TO_YCBCR_CSC, and it will be reasonably obvious that its
value describes the output data rather than the input data.

Source and sink have a slight connotation in my mind wrt. the box that
produces the display signal and the box that eats the signal. So trying
to use the same terms to describe the internals of the pipeline inside
the "source box" migth lead to some confusion. But we do probably need
some decent names for these to make the layout of the pipeline clear.
Input/output are the other names that popped to my mind but those aren't
necessarily any 

Re: DRM Atomic property for color-space conversion

[Ville Syrjälä]

On Thu, Mar 16, 2017 at 04:20:29PM +0200, Sharma, Shashank wrote:
> Regards
> 
> Shashank
> 
> 
> On 3/16/2017 4:07 PM, Ville Syrjälä wrote:
> > On Tue, Jan 31, 2017 at 03:55:41PM +, Brian Starkey wrote:
> >> On Tue, Jan 31, 2017 at 05:15:46PM +0200, Ville Syrjälä wrote:
> >>> On Tue, Jan 31, 2017 at 12:33:29PM +, Brian Starkey wrote:
>  Hi,
> 
>  On Mon, Jan 30, 2017 at 03:35:13PM +0200, Ville Syrjälä wrote:
> > On Fri, Jan 27, 2017 at 05:23:24PM +, Brian Starkey wrote:
> >> Hi,
> >>
> >> We're looking to enable the per-plane color management hardware in
> >> Mali-DP with atomic properties, which has sparked some conversation
> >> around how to handle YCbCr formats.
> >>
> >> As it stands today, it's assumed that a driver will implicitly "do the
> >> right thing" to display a YCbCr buffer.
> >>
> >> YCbCr data often uses different gamma curves and signal ranges (e.g.
> >> BT.609, BT.701, BT.2020, studio range, full-range), so its desirable
> >> to be able to explicitly control the YCbCr to RGB conversion process
> >> from userspace.
> >>
> >> We're proposing adding a "CSC" (color-space conversion) property to
> >> control this - primarily per-plane for framebuffer->pipeline CSC, but
> >> perhaps one per CRTC too for devices which have an RGB pipeline and
> >> want to output in YUV to the display:
> >>
> >> Name: "CSC"
> >> Type: ENUM | ATOMIC;
> >> Enum values (representative):
> >> "default":
> >>Same behaviour as now. "Some kind" of YCbCr->RGB conversion
> >>for YCbCr buffers, bypass for RGB buffers
> >> "disable":
> >>Explicitly disable all colorspace conversion (i.e. use an
> >>identity matrix).
> >> "YCbCr to RGB: BT.709":
> >>Only valid for YCbCr formats. CSC in accordance with BT.709
> >>using [16..235] for (8-bit) luma values, and [16..240] for
> >>8-bit chroma values. For 10-bit formats, the range limits are
> >>multiplied by 4.
> >> "YCbCr to RGB: BT.709 full-swing":
> >>Only valid for YCbCr formats. CSC in accordance with BT.709,
> >>but using the full range of each channel.
> >> "YCbCr to RGB: Use CTM":*
> >>Only valid for YCbCr formats. Use the matrix applied via the
> >>plane's CTM property
> >> "RGB to RGB: Use CTM":*
> >>Only valid for RGB formats. Use the matrix applied via the
> >>plane's CTM property
> >> "Use CTM":*
> >>Valid for any format. Use the matrix applied via the plane's
> >>CTM property
> >> ... any other values for BT.601, BT.2020, RGB to YCbCr etc. etc. as
> >> they are required.
> > Having some RGB2RGB and YCBCR2RGB things in the same property seems
> > weird. I would just go with something very simple like:
> >
> > YCBCR_TO_RGB_CSC:
> > * BT.601
> > * BT.709
> > * custom matrix
> >
>  I think we've agreed in #dri-devel that this CSC property
>  can't/shouldn't be mapped on-to the existing (hardware implementing
>  the) CTM property - even in the case of per-plane color management -
>  because CSC needs to be done before DEGAMMA.
> 
>  So, I'm in favour of going with what you suggested in the first place:
> 
>  A new YCBCR_TO_RGB_CSC property, enum type, with a list of fixed
>  conversions. I'd drop the custom matrix for now, as we'd need to add
>  another property to attach the custom matrix blob too.
> 
>  I still think we need a way to specify whether the source data range
>  is broadcast/full-range, so perhaps the enum list should be expanded
>  to all combinations of BT.601/BT.709 + broadcast/full-range.
> >>> Sounds reasonable. Not that much full range YCbCr stuff out there
> >>> perhaps. Well, apart from jpegs I suppose. But no harm in being able
> >>> to deal with it.
> >>>
>  (I'm not sure what the canonical naming for broadcast/full-range is,
>  we call them narrow and wide)
> >>> We tend to call them full vs. limited range. That's how our
> >>> "Broadcast RGB" property is defined as well.
> >>>
> >> OK, using the same ones sounds sensible.
> >>
> > And trying to use the same thing for the crtc stuff is probably not
> > going to end well. Like Daniel said we already have the
> > 'Broadcast RGB' property muddying the waters there, and that stuff
> > also ties in with what colorspace we signal to the sink via
> > infoframes/whatever the DP thing was called. So my gut feeling is
> > that trying to use the same property everywhere will just end up
> > messy.
>  Yeah, agreed. If/when someone wants to add CSC on the output of a CRTC
>  (after GAMMA), we can add a new property.
> 
>  That makes me wonder about calling this one SOURCE_YCBCR_TO_RGB_CSC to
>  be explicit that it describes the 

Re: DRM Atomic property for color-space conversion

[Ville Syrjälä]

On Thu, Mar 16, 2017 at 04:20:29PM +0200, Sharma, Shashank wrote:
> Regards
> 
> Shashank
> 
> 
> On 3/16/2017 4:07 PM, Ville Syrjälä wrote:
> > On Tue, Jan 31, 2017 at 03:55:41PM +, Brian Starkey wrote:
> >> On Tue, Jan 31, 2017 at 05:15:46PM +0200, Ville Syrjälä wrote:
> >>> On Tue, Jan 31, 2017 at 12:33:29PM +, Brian Starkey wrote:
>  Hi,
> 
>  On Mon, Jan 30, 2017 at 03:35:13PM +0200, Ville Syrjälä wrote:
> > On Fri, Jan 27, 2017 at 05:23:24PM +, Brian Starkey wrote:
> >> Hi,
> >>
> >> We're looking to enable the per-plane color management hardware in
> >> Mali-DP with atomic properties, which has sparked some conversation
> >> around how to handle YCbCr formats.
> >>
> >> As it stands today, it's assumed that a driver will implicitly "do the
> >> right thing" to display a YCbCr buffer.
> >>
> >> YCbCr data often uses different gamma curves and signal ranges (e.g.
> >> BT.609, BT.701, BT.2020, studio range, full-range), so its desirable
> >> to be able to explicitly control the YCbCr to RGB conversion process
> >> from userspace.
> >>
> >> We're proposing adding a "CSC" (color-space conversion) property to
> >> control this - primarily per-plane for framebuffer->pipeline CSC, but
> >> perhaps one per CRTC too for devices which have an RGB pipeline and
> >> want to output in YUV to the display:
> >>
> >> Name: "CSC"
> >> Type: ENUM | ATOMIC;
> >> Enum values (representative):
> >> "default":
> >>Same behaviour as now. "Some kind" of YCbCr->RGB conversion
> >>for YCbCr buffers, bypass for RGB buffers
> >> "disable":
> >>Explicitly disable all colorspace conversion (i.e. use an
> >>identity matrix).
> >> "YCbCr to RGB: BT.709":
> >>Only valid for YCbCr formats. CSC in accordance with BT.709
> >>using [16..235] for (8-bit) luma values, and [16..240] for
> >>8-bit chroma values. For 10-bit formats, the range limits are
> >>multiplied by 4.
> >> "YCbCr to RGB: BT.709 full-swing":
> >>Only valid for YCbCr formats. CSC in accordance with BT.709,
> >>but using the full range of each channel.
> >> "YCbCr to RGB: Use CTM":*
> >>Only valid for YCbCr formats. Use the matrix applied via the
> >>plane's CTM property
> >> "RGB to RGB: Use CTM":*
> >>Only valid for RGB formats. Use the matrix applied via the
> >>plane's CTM property
> >> "Use CTM":*
> >>Valid for any format. Use the matrix applied via the plane's
> >>CTM property
> >> ... any other values for BT.601, BT.2020, RGB to YCbCr etc. etc. as
> >> they are required.
> > Having some RGB2RGB and YCBCR2RGB things in the same property seems
> > weird. I would just go with something very simple like:
> >
> > YCBCR_TO_RGB_CSC:
> > * BT.601
> > * BT.709
> > * custom matrix
> >
>  I think we've agreed in #dri-devel that this CSC property
>  can't/shouldn't be mapped on-to the existing (hardware implementing
>  the) CTM property - even in the case of per-plane color management -
>  because CSC needs to be done before DEGAMMA.
> 
>  So, I'm in favour of going with what you suggested in the first place:
> 
>  A new YCBCR_TO_RGB_CSC property, enum type, with a list of fixed
>  conversions. I'd drop the custom matrix for now, as we'd need to add
>  another property to attach the custom matrix blob too.
> 
>  I still think we need a way to specify whether the source data range
>  is broadcast/full-range, so perhaps the enum list should be expanded
>  to all combinations of BT.601/BT.709 + broadcast/full-range.
> >>> Sounds reasonable. Not that much full range YCbCr stuff out there
> >>> perhaps. Well, apart from jpegs I suppose. But no harm in being able
> >>> to deal with it.
> >>>
>  (I'm not sure what the canonical naming for broadcast/full-range is,
>  we call them narrow and wide)
> >>> We tend to call them full vs. limited range. That's how our
> >>> "Broadcast RGB" property is defined as well.
> >>>
> >> OK, using the same ones sounds sensible.
> >>
> > And trying to use the same thing for the crtc stuff is probably not
> > going to end well. Like Daniel said we already have the
> > 'Broadcast RGB' property muddying the waters there, and that stuff
> > also ties in with what colorspace we signal to the sink via
> > infoframes/whatever the DP thing was called. So my gut feeling is
> > that trying to use the same property everywhere will just end up
> > messy.
>  Yeah, agreed. If/when someone wants to add CSC on the output of a CRTC
>  (after GAMMA), we can add a new property.
> 
>  That makes me wonder about calling this one SOURCE_YCBCR_TO_RGB_CSC to
>  be explicit that it describes the 

Re: DRM Atomic property for color-space conversion

[Local user for Liviu Dudau]

On Thu, Mar 16, 2017 at 04:30:59PM +0200, Ville Syrjälä wrote:
> On Thu, Mar 16, 2017 at 04:20:29PM +0200, Sharma, Shashank wrote:
> > Regards
> > 
> > Shashank
> > 
> > 
> > On 3/16/2017 4:07 PM, Ville Syrjälä wrote:
> > > On Tue, Jan 31, 2017 at 03:55:41PM +, Brian Starkey wrote:
> > >> On Tue, Jan 31, 2017 at 05:15:46PM +0200, Ville Syrjälä wrote:
> > >>> On Tue, Jan 31, 2017 at 12:33:29PM +, Brian Starkey wrote:
> >  Hi,
> > 
> >  On Mon, Jan 30, 2017 at 03:35:13PM +0200, Ville Syrjälä wrote:
> > > On Fri, Jan 27, 2017 at 05:23:24PM +, Brian Starkey wrote:
> > >> Hi,
> > >>
> > >> We're looking to enable the per-plane color management hardware in
> > >> Mali-DP with atomic properties, which has sparked some conversation
> > >> around how to handle YCbCr formats.
> > >>
> > >> As it stands today, it's assumed that a driver will implicitly "do 
> > >> the
> > >> right thing" to display a YCbCr buffer.
> > >>
> > >> YCbCr data often uses different gamma curves and signal ranges (e.g.
> > >> BT.609, BT.701, BT.2020, studio range, full-range), so its desirable
> > >> to be able to explicitly control the YCbCr to RGB conversion process
> > >> from userspace.
> > >>
> > >> We're proposing adding a "CSC" (color-space conversion) property to
> > >> control this - primarily per-plane for framebuffer->pipeline CSC, but
> > >> perhaps one per CRTC too for devices which have an RGB pipeline and
> > >> want to output in YUV to the display:
> > >>
> > >> Name: "CSC"
> > >> Type: ENUM | ATOMIC;
> > >> Enum values (representative):
> > >> "default":
> > >>  Same behaviour as now. "Some kind" of YCbCr->RGB conversion
> > >>  for YCbCr buffers, bypass for RGB buffers
> > >> "disable":
> > >>  Explicitly disable all colorspace conversion (i.e. use an
> > >>  identity matrix).
> > >> "YCbCr to RGB: BT.709":
> > >>  Only valid for YCbCr formats. CSC in accordance with BT.709
> > >>  using [16..235] for (8-bit) luma values, and [16..240] for
> > >>  8-bit chroma values. For 10-bit formats, the range limits are
> > >>  multiplied by 4.
> > >> "YCbCr to RGB: BT.709 full-swing":
> > >>  Only valid for YCbCr formats. CSC in accordance with BT.709,
> > >>  but using the full range of each channel.
> > >> "YCbCr to RGB: Use CTM":*
> > >>  Only valid for YCbCr formats. Use the matrix applied via the
> > >>  plane's CTM property
> > >> "RGB to RGB: Use CTM":*
> > >>  Only valid for RGB formats. Use the matrix applied via the
> > >>  plane's CTM property
> > >> "Use CTM":*
> > >>  Valid for any format. Use the matrix applied via the plane's
> > >>  CTM property
> > >> ... any other values for BT.601, BT.2020, RGB to YCbCr etc. etc. as
> > >> they are required.
> > > Having some RGB2RGB and YCBCR2RGB things in the same property seems
> > > weird. I would just go with something very simple like:
> > >
> > > YCBCR_TO_RGB_CSC:
> > > * BT.601
> > > * BT.709
> > > * custom matrix
> > >
> >  I think we've agreed in #dri-devel that this CSC property
> >  can't/shouldn't be mapped on-to the existing (hardware implementing
> >  the) CTM property - even in the case of per-plane color management -
> >  because CSC needs to be done before DEGAMMA.
> > 
> >  So, I'm in favour of going with what you suggested in the first place:
> > 
> >  A new YCBCR_TO_RGB_CSC property, enum type, with a list of fixed
> >  conversions. I'd drop the custom matrix for now, as we'd need to add
> >  another property to attach the custom matrix blob too.
> > 
> >  I still think we need a way to specify whether the source data range
> >  is broadcast/full-range, so perhaps the enum list should be expanded
> >  to all combinations of BT.601/BT.709 + broadcast/full-range.
> > >>> Sounds reasonable. Not that much full range YCbCr stuff out there
> > >>> perhaps. Well, apart from jpegs I suppose. But no harm in being able
> > >>> to deal with it.
> > >>>
> >  (I'm not sure what the canonical naming for broadcast/full-range is,
> >  we call them narrow and wide)
> > >>> We tend to call them full vs. limited range. That's how our
> > >>> "Broadcast RGB" property is defined as well.
> > >>>
> > >> OK, using the same ones sounds sensible.
> > >>
> > > And trying to use the same thing for the crtc stuff is probably not
> > > going to end well. Like Daniel said we already have the
> > > 'Broadcast RGB' property muddying the waters there, and that stuff
> > > also ties in with what colorspace we signal to the sink via
> > > infoframes/whatever the DP thing was called. So my gut feeling is
> > > that trying to use the same property everywhere will just end up
> > > messy.
> >  

Re: DRM Atomic property for color-space conversion

[Local user for Liviu Dudau]

On Thu, Mar 16, 2017 at 04:30:59PM +0200, Ville Syrjälä wrote:
> On Thu, Mar 16, 2017 at 04:20:29PM +0200, Sharma, Shashank wrote:
> > Regards
> > 
> > Shashank
> > 
> > 
> > On 3/16/2017 4:07 PM, Ville Syrjälä wrote:
> > > On Tue, Jan 31, 2017 at 03:55:41PM +, Brian Starkey wrote:
> > >> On Tue, Jan 31, 2017 at 05:15:46PM +0200, Ville Syrjälä wrote:
> > >>> On Tue, Jan 31, 2017 at 12:33:29PM +, Brian Starkey wrote:
> >  Hi,
> > 
> >  On Mon, Jan 30, 2017 at 03:35:13PM +0200, Ville Syrjälä wrote:
> > > On Fri, Jan 27, 2017 at 05:23:24PM +, Brian Starkey wrote:
> > >> Hi,
> > >>
> > >> We're looking to enable the per-plane color management hardware in
> > >> Mali-DP with atomic properties, which has sparked some conversation
> > >> around how to handle YCbCr formats.
> > >>
> > >> As it stands today, it's assumed that a driver will implicitly "do 
> > >> the
> > >> right thing" to display a YCbCr buffer.
> > >>
> > >> YCbCr data often uses different gamma curves and signal ranges (e.g.
> > >> BT.609, BT.701, BT.2020, studio range, full-range), so its desirable
> > >> to be able to explicitly control the YCbCr to RGB conversion process
> > >> from userspace.
> > >>
> > >> We're proposing adding a "CSC" (color-space conversion) property to
> > >> control this - primarily per-plane for framebuffer->pipeline CSC, but
> > >> perhaps one per CRTC too for devices which have an RGB pipeline and
> > >> want to output in YUV to the display:
> > >>
> > >> Name: "CSC"
> > >> Type: ENUM | ATOMIC;
> > >> Enum values (representative):
> > >> "default":
> > >>  Same behaviour as now. "Some kind" of YCbCr->RGB conversion
> > >>  for YCbCr buffers, bypass for RGB buffers
> > >> "disable":
> > >>  Explicitly disable all colorspace conversion (i.e. use an
> > >>  identity matrix).
> > >> "YCbCr to RGB: BT.709":
> > >>  Only valid for YCbCr formats. CSC in accordance with BT.709
> > >>  using [16..235] for (8-bit) luma values, and [16..240] for
> > >>  8-bit chroma values. For 10-bit formats, the range limits are
> > >>  multiplied by 4.
> > >> "YCbCr to RGB: BT.709 full-swing":
> > >>  Only valid for YCbCr formats. CSC in accordance with BT.709,
> > >>  but using the full range of each channel.
> > >> "YCbCr to RGB: Use CTM":*
> > >>  Only valid for YCbCr formats. Use the matrix applied via the
> > >>  plane's CTM property
> > >> "RGB to RGB: Use CTM":*
> > >>  Only valid for RGB formats. Use the matrix applied via the
> > >>  plane's CTM property
> > >> "Use CTM":*
> > >>  Valid for any format. Use the matrix applied via the plane's
> > >>  CTM property
> > >> ... any other values for BT.601, BT.2020, RGB to YCbCr etc. etc. as
> > >> they are required.
> > > Having some RGB2RGB and YCBCR2RGB things in the same property seems
> > > weird. I would just go with something very simple like:
> > >
> > > YCBCR_TO_RGB_CSC:
> > > * BT.601
> > > * BT.709
> > > * custom matrix
> > >
> >  I think we've agreed in #dri-devel that this CSC property
> >  can't/shouldn't be mapped on-to the existing (hardware implementing
> >  the) CTM property - even in the case of per-plane color management -
> >  because CSC needs to be done before DEGAMMA.
> > 
> >  So, I'm in favour of going with what you suggested in the first place:
> > 
> >  A new YCBCR_TO_RGB_CSC property, enum type, with a list of fixed
> >  conversions. I'd drop the custom matrix for now, as we'd need to add
> >  another property to attach the custom matrix blob too.
> > 
> >  I still think we need a way to specify whether the source data range
> >  is broadcast/full-range, so perhaps the enum list should be expanded
> >  to all combinations of BT.601/BT.709 + broadcast/full-range.
> > >>> Sounds reasonable. Not that much full range YCbCr stuff out there
> > >>> perhaps. Well, apart from jpegs I suppose. But no harm in being able
> > >>> to deal with it.
> > >>>
> >  (I'm not sure what the canonical naming for broadcast/full-range is,
> >  we call them narrow and wide)
> > >>> We tend to call them full vs. limited range. That's how our
> > >>> "Broadcast RGB" property is defined as well.
> > >>>
> > >> OK, using the same ones sounds sensible.
> > >>
> > > And trying to use the same thing for the crtc stuff is probably not
> > > going to end well. Like Daniel said we already have the
> > > 'Broadcast RGB' property muddying the waters there, and that stuff
> > > also ties in with what colorspace we signal to the sink via
> > > infoframes/whatever the DP thing was called. So my gut feeling is
> > > that trying to use the same property everywhere will just end up
> > > messy.
> >  

Re: DRM Atomic property for color-space conversion

[Sharma, Shashank]

Regards

Shashank


On 3/16/2017 4:07 PM, Ville Syrjälä wrote:

On Tue, Jan 31, 2017 at 03:55:41PM +, Brian Starkey wrote:

On Tue, Jan 31, 2017 at 05:15:46PM +0200, Ville Syrjälä wrote:

On Tue, Jan 31, 2017 at 12:33:29PM +, Brian Starkey wrote:

Hi,

On Mon, Jan 30, 2017 at 03:35:13PM +0200, Ville Syrjälä wrote:

On Fri, Jan 27, 2017 at 05:23:24PM +, Brian Starkey wrote:

Hi,

We're looking to enable the per-plane color management hardware in
Mali-DP with atomic properties, which has sparked some conversation
around how to handle YCbCr formats.

As it stands today, it's assumed that a driver will implicitly "do the
right thing" to display a YCbCr buffer.

YCbCr data often uses different gamma curves and signal ranges (e.g.
BT.609, BT.701, BT.2020, studio range, full-range), so its desirable
to be able to explicitly control the YCbCr to RGB conversion process
from userspace.

We're proposing adding a "CSC" (color-space conversion) property to
control this - primarily per-plane for framebuffer->pipeline CSC, but
perhaps one per CRTC too for devices which have an RGB pipeline and
want to output in YUV to the display:

Name: "CSC"
Type: ENUM | ATOMIC;
Enum values (representative):
"default":
Same behaviour as now. "Some kind" of YCbCr->RGB conversion
for YCbCr buffers, bypass for RGB buffers
"disable":
Explicitly disable all colorspace conversion (i.e. use an
identity matrix).
"YCbCr to RGB: BT.709":
Only valid for YCbCr formats. CSC in accordance with BT.709
using [16..235] for (8-bit) luma values, and [16..240] for
8-bit chroma values. For 10-bit formats, the range limits are
multiplied by 4.
"YCbCr to RGB: BT.709 full-swing":
Only valid for YCbCr formats. CSC in accordance with BT.709,
but using the full range of each channel.
"YCbCr to RGB: Use CTM":*
Only valid for YCbCr formats. Use the matrix applied via the
plane's CTM property
"RGB to RGB: Use CTM":*
Only valid for RGB formats. Use the matrix applied via the
plane's CTM property
"Use CTM":*
Valid for any format. Use the matrix applied via the plane's
CTM property
... any other values for BT.601, BT.2020, RGB to YCbCr etc. etc. as
they are required.

Having some RGB2RGB and YCBCR2RGB things in the same property seems
weird. I would just go with something very simple like:

YCBCR_TO_RGB_CSC:
* BT.601
* BT.709
* custom matrix


I think we've agreed in #dri-devel that this CSC property
can't/shouldn't be mapped on-to the existing (hardware implementing
the) CTM property - even in the case of per-plane color management -
because CSC needs to be done before DEGAMMA.

So, I'm in favour of going with what you suggested in the first place:

A new YCBCR_TO_RGB_CSC property, enum type, with a list of fixed
conversions. I'd drop the custom matrix for now, as we'd need to add
another property to attach the custom matrix blob too.

I still think we need a way to specify whether the source data range
is broadcast/full-range, so perhaps the enum list should be expanded
to all combinations of BT.601/BT.709 + broadcast/full-range.

Sounds reasonable. Not that much full range YCbCr stuff out there
perhaps. Well, apart from jpegs I suppose. But no harm in being able
to deal with it.


(I'm not sure what the canonical naming for broadcast/full-range is,
we call them narrow and wide)

We tend to call them full vs. limited range. That's how our
"Broadcast RGB" property is defined as well.


OK, using the same ones sounds sensible.


And trying to use the same thing for the crtc stuff is probably not
going to end well. Like Daniel said we already have the
'Broadcast RGB' property muddying the waters there, and that stuff
also ties in with what colorspace we signal to the sink via
infoframes/whatever the DP thing was called. So my gut feeling is
that trying to use the same property everywhere will just end up
messy.

Yeah, agreed. If/when someone wants to add CSC on the output of a CRTC
(after GAMMA), we can add a new property.

That makes me wonder about calling this one SOURCE_YCBCR_TO_RGB_CSC to
be explicit that it describes the source data. Then we can later add
SINK_RGB_TO_YCBCR_CSC, and it will be reasonably obvious that its
value describes the output data rather than the input data.

Source and sink have a slight connotation in my mind wrt. the box that
produces the display signal and the box that eats the signal. So trying
to use the same terms to describe the internals of the pipeline inside
the "source box" migth lead to some confusion. But we do probably need
some decent names for these to make the layout of the pipeline clear.
Input/output are the other names that popped to my mind but those aren't
necessarily any better. But in the end I think I could live with whatever
names we happen to pick, as long as we document the pipeline clearly.

Long ago I did wonder if we should just start indexing these things
somehow, and 

Re: DRM Atomic property for color-space conversion

[Sharma, Shashank]

Regards

Shashank


On 3/16/2017 4:07 PM, Ville Syrjälä wrote:

On Tue, Jan 31, 2017 at 03:55:41PM +, Brian Starkey wrote:

On Tue, Jan 31, 2017 at 05:15:46PM +0200, Ville Syrjälä wrote:

On Tue, Jan 31, 2017 at 12:33:29PM +, Brian Starkey wrote:

Hi,

On Mon, Jan 30, 2017 at 03:35:13PM +0200, Ville Syrjälä wrote:

On Fri, Jan 27, 2017 at 05:23:24PM +, Brian Starkey wrote:

Hi,

We're looking to enable the per-plane color management hardware in
Mali-DP with atomic properties, which has sparked some conversation
around how to handle YCbCr formats.

As it stands today, it's assumed that a driver will implicitly "do the
right thing" to display a YCbCr buffer.

YCbCr data often uses different gamma curves and signal ranges (e.g.
BT.609, BT.701, BT.2020, studio range, full-range), so its desirable
to be able to explicitly control the YCbCr to RGB conversion process
from userspace.

We're proposing adding a "CSC" (color-space conversion) property to
control this - primarily per-plane for framebuffer->pipeline CSC, but
perhaps one per CRTC too for devices which have an RGB pipeline and
want to output in YUV to the display:

Name: "CSC"
Type: ENUM | ATOMIC;
Enum values (representative):
"default":
Same behaviour as now. "Some kind" of YCbCr->RGB conversion
for YCbCr buffers, bypass for RGB buffers
"disable":
Explicitly disable all colorspace conversion (i.e. use an
identity matrix).
"YCbCr to RGB: BT.709":
Only valid for YCbCr formats. CSC in accordance with BT.709
using [16..235] for (8-bit) luma values, and [16..240] for
8-bit chroma values. For 10-bit formats, the range limits are
multiplied by 4.
"YCbCr to RGB: BT.709 full-swing":
Only valid for YCbCr formats. CSC in accordance with BT.709,
but using the full range of each channel.
"YCbCr to RGB: Use CTM":*
Only valid for YCbCr formats. Use the matrix applied via the
plane's CTM property
"RGB to RGB: Use CTM":*
Only valid for RGB formats. Use the matrix applied via the
plane's CTM property
"Use CTM":*
Valid for any format. Use the matrix applied via the plane's
CTM property
... any other values for BT.601, BT.2020, RGB to YCbCr etc. etc. as
they are required.

Having some RGB2RGB and YCBCR2RGB things in the same property seems
weird. I would just go with something very simple like:

YCBCR_TO_RGB_CSC:
* BT.601
* BT.709
* custom matrix


I think we've agreed in #dri-devel that this CSC property
can't/shouldn't be mapped on-to the existing (hardware implementing
the) CTM property - even in the case of per-plane color management -
because CSC needs to be done before DEGAMMA.

So, I'm in favour of going with what you suggested in the first place:

A new YCBCR_TO_RGB_CSC property, enum type, with a list of fixed
conversions. I'd drop the custom matrix for now, as we'd need to add
another property to attach the custom matrix blob too.

I still think we need a way to specify whether the source data range
is broadcast/full-range, so perhaps the enum list should be expanded
to all combinations of BT.601/BT.709 + broadcast/full-range.

Sounds reasonable. Not that much full range YCbCr stuff out there
perhaps. Well, apart from jpegs I suppose. But no harm in being able
to deal with it.


(I'm not sure what the canonical naming for broadcast/full-range is,
we call them narrow and wide)

We tend to call them full vs. limited range. That's how our
"Broadcast RGB" property is defined as well.


OK, using the same ones sounds sensible.


And trying to use the same thing for the crtc stuff is probably not
going to end well. Like Daniel said we already have the
'Broadcast RGB' property muddying the waters there, and that stuff
also ties in with what colorspace we signal to the sink via
infoframes/whatever the DP thing was called. So my gut feeling is
that trying to use the same property everywhere will just end up
messy.

Yeah, agreed. If/when someone wants to add CSC on the output of a CRTC
(after GAMMA), we can add a new property.

That makes me wonder about calling this one SOURCE_YCBCR_TO_RGB_CSC to
be explicit that it describes the source data. Then we can later add
SINK_RGB_TO_YCBCR_CSC, and it will be reasonably obvious that its
value describes the output data rather than the input data.

Source and sink have a slight connotation in my mind wrt. the box that
produces the display signal and the box that eats the signal. So trying
to use the same terms to describe the internals of the pipeline inside
the "source box" migth lead to some confusion. But we do probably need
some decent names for these to make the layout of the pipeline clear.
Input/output are the other names that popped to my mind but those aren't
necessarily any better. But in the end I think I could live with whatever
names we happen to pick, as long as we document the pipeline clearly.

Long ago I did wonder if we should just start indexing these things
somehow, and 

Re: DRM Atomic property for color-space conversion

[Alex Deucher]

On Thu, Mar 16, 2017 at 10:07 AM, Ville Syrjälä
 wrote:
> On Tue, Jan 31, 2017 at 03:55:41PM +, Brian Starkey wrote:
>> On Tue, Jan 31, 2017 at 05:15:46PM +0200, Ville Syrjälä wrote:
>> >On Tue, Jan 31, 2017 at 12:33:29PM +, Brian Starkey wrote:
>> >> Hi,
>> >>
>> >> On Mon, Jan 30, 2017 at 03:35:13PM +0200, Ville Syrjälä wrote:
>> >> >On Fri, Jan 27, 2017 at 05:23:24PM +, Brian Starkey wrote:
>> >> >> Hi,
>> >> >>
>> >> >> We're looking to enable the per-plane color management hardware in
>> >> >> Mali-DP with atomic properties, which has sparked some conversation
>> >> >> around how to handle YCbCr formats.
>> >> >>
>> >> >> As it stands today, it's assumed that a driver will implicitly "do the
>> >> >> right thing" to display a YCbCr buffer.
>> >> >>
>> >> >> YCbCr data often uses different gamma curves and signal ranges (e.g.
>> >> >> BT.609, BT.701, BT.2020, studio range, full-range), so its desirable
>> >> >> to be able to explicitly control the YCbCr to RGB conversion process
>> >> >> from userspace.
>> >> >>
>> >> >> We're proposing adding a "CSC" (color-space conversion) property to
>> >> >> control this - primarily per-plane for framebuffer->pipeline CSC, but
>> >> >> perhaps one per CRTC too for devices which have an RGB pipeline and
>> >> >> want to output in YUV to the display:
>> >> >>
>> >> >> Name: "CSC"
>> >> >> Type: ENUM | ATOMIC;
>> >> >> Enum values (representative):
>> >> >> "default":
>> >> >> Same behaviour as now. "Some kind" of YCbCr->RGB conversion
>> >> >> for YCbCr buffers, bypass for RGB buffers
>> >> >> "disable":
>> >> >> Explicitly disable all colorspace conversion (i.e. use an
>> >> >> identity matrix).
>> >> >> "YCbCr to RGB: BT.709":
>> >> >> Only valid for YCbCr formats. CSC in accordance with BT.709
>> >> >> using [16..235] for (8-bit) luma values, and [16..240] for
>> >> >> 8-bit chroma values. For 10-bit formats, the range limits are
>> >> >> multiplied by 4.
>> >> >> "YCbCr to RGB: BT.709 full-swing":
>> >> >> Only valid for YCbCr formats. CSC in accordance with BT.709,
>> >> >> but using the full range of each channel.
>> >> >> "YCbCr to RGB: Use CTM":*
>> >> >> Only valid for YCbCr formats. Use the matrix applied via the
>> >> >> plane's CTM property
>> >> >> "RGB to RGB: Use CTM":*
>> >> >> Only valid for RGB formats. Use the matrix applied via the
>> >> >> plane's CTM property
>> >> >> "Use CTM":*
>> >> >> Valid for any format. Use the matrix applied via the plane's
>> >> >> CTM property
>> >> >> ... any other values for BT.601, BT.2020, RGB to YCbCr etc. etc. as
>> >> >> they are required.
>> >> >
>> >> >Having some RGB2RGB and YCBCR2RGB things in the same property seems
>> >> >weird. I would just go with something very simple like:
>> >> >
>> >> >YCBCR_TO_RGB_CSC:
>> >> >* BT.601
>> >> >* BT.709
>> >> >* custom matrix
>> >> >
>> >>
>> >> I think we've agreed in #dri-devel that this CSC property
>> >> can't/shouldn't be mapped on-to the existing (hardware implementing
>> >> the) CTM property - even in the case of per-plane color management -
>> >> because CSC needs to be done before DEGAMMA.
>> >>
>> >> So, I'm in favour of going with what you suggested in the first place:
>> >>
>> >> A new YCBCR_TO_RGB_CSC property, enum type, with a list of fixed
>> >> conversions. I'd drop the custom matrix for now, as we'd need to add
>> >> another property to attach the custom matrix blob too.
>> >>
>> >> I still think we need a way to specify whether the source data range
>> >> is broadcast/full-range, so perhaps the enum list should be expanded
>> >> to all combinations of BT.601/BT.709 + broadcast/full-range.
>> >
>> >Sounds reasonable. Not that much full range YCbCr stuff out there
>> >perhaps. Well, apart from jpegs I suppose. But no harm in being able
>> >to deal with it.
>> >
>> >>
>> >> (I'm not sure what the canonical naming for broadcast/full-range is,
>> >> we call them narrow and wide)
>> >
>> >We tend to call them full vs. limited range. That's how our
>> >"Broadcast RGB" property is defined as well.
>> >
>>
>> OK, using the same ones sounds sensible.
>>
>> >>
>> >> >And trying to use the same thing for the crtc stuff is probably not
>> >> >going to end well. Like Daniel said we already have the
>> >> >'Broadcast RGB' property muddying the waters there, and that stuff
>> >> >also ties in with what colorspace we signal to the sink via
>> >> >infoframes/whatever the DP thing was called. So my gut feeling is
>> >> >that trying to use the same property everywhere will just end up
>> >> >messy.
>> >>
>> >> Yeah, agreed. If/when someone wants to add CSC on the output of a CRTC
>> >> (after GAMMA), we can add a new property.
>> >>
>> >> That makes me wonder about calling this one SOURCE_YCBCR_TO_RGB_CSC to
>> >> be explicit that it describes the source data. Then we can later add
>> >> 

Re: DRM Atomic property for color-space conversion

[Alex Deucher]

On Thu, Mar 16, 2017 at 10:07 AM, Ville Syrjälä
 wrote:
> On Tue, Jan 31, 2017 at 03:55:41PM +, Brian Starkey wrote:
>> On Tue, Jan 31, 2017 at 05:15:46PM +0200, Ville Syrjälä wrote:
>> >On Tue, Jan 31, 2017 at 12:33:29PM +, Brian Starkey wrote:
>> >> Hi,
>> >>
>> >> On Mon, Jan 30, 2017 at 03:35:13PM +0200, Ville Syrjälä wrote:
>> >> >On Fri, Jan 27, 2017 at 05:23:24PM +, Brian Starkey wrote:
>> >> >> Hi,
>> >> >>
>> >> >> We're looking to enable the per-plane color management hardware in
>> >> >> Mali-DP with atomic properties, which has sparked some conversation
>> >> >> around how to handle YCbCr formats.
>> >> >>
>> >> >> As it stands today, it's assumed that a driver will implicitly "do the
>> >> >> right thing" to display a YCbCr buffer.
>> >> >>
>> >> >> YCbCr data often uses different gamma curves and signal ranges (e.g.
>> >> >> BT.609, BT.701, BT.2020, studio range, full-range), so its desirable
>> >> >> to be able to explicitly control the YCbCr to RGB conversion process
>> >> >> from userspace.
>> >> >>
>> >> >> We're proposing adding a "CSC" (color-space conversion) property to
>> >> >> control this - primarily per-plane for framebuffer->pipeline CSC, but
>> >> >> perhaps one per CRTC too for devices which have an RGB pipeline and
>> >> >> want to output in YUV to the display:
>> >> >>
>> >> >> Name: "CSC"
>> >> >> Type: ENUM | ATOMIC;
>> >> >> Enum values (representative):
>> >> >> "default":
>> >> >> Same behaviour as now. "Some kind" of YCbCr->RGB conversion
>> >> >> for YCbCr buffers, bypass for RGB buffers
>> >> >> "disable":
>> >> >> Explicitly disable all colorspace conversion (i.e. use an
>> >> >> identity matrix).
>> >> >> "YCbCr to RGB: BT.709":
>> >> >> Only valid for YCbCr formats. CSC in accordance with BT.709
>> >> >> using [16..235] for (8-bit) luma values, and [16..240] for
>> >> >> 8-bit chroma values. For 10-bit formats, the range limits are
>> >> >> multiplied by 4.
>> >> >> "YCbCr to RGB: BT.709 full-swing":
>> >> >> Only valid for YCbCr formats. CSC in accordance with BT.709,
>> >> >> but using the full range of each channel.
>> >> >> "YCbCr to RGB: Use CTM":*
>> >> >> Only valid for YCbCr formats. Use the matrix applied via the
>> >> >> plane's CTM property
>> >> >> "RGB to RGB: Use CTM":*
>> >> >> Only valid for RGB formats. Use the matrix applied via the
>> >> >> plane's CTM property
>> >> >> "Use CTM":*
>> >> >> Valid for any format. Use the matrix applied via the plane's
>> >> >> CTM property
>> >> >> ... any other values for BT.601, BT.2020, RGB to YCbCr etc. etc. as
>> >> >> they are required.
>> >> >
>> >> >Having some RGB2RGB and YCBCR2RGB things in the same property seems
>> >> >weird. I would just go with something very simple like:
>> >> >
>> >> >YCBCR_TO_RGB_CSC:
>> >> >* BT.601
>> >> >* BT.709
>> >> >* custom matrix
>> >> >
>> >>
>> >> I think we've agreed in #dri-devel that this CSC property
>> >> can't/shouldn't be mapped on-to the existing (hardware implementing
>> >> the) CTM property - even in the case of per-plane color management -
>> >> because CSC needs to be done before DEGAMMA.
>> >>
>> >> So, I'm in favour of going with what you suggested in the first place:
>> >>
>> >> A new YCBCR_TO_RGB_CSC property, enum type, with a list of fixed
>> >> conversions. I'd drop the custom matrix for now, as we'd need to add
>> >> another property to attach the custom matrix blob too.
>> >>
>> >> I still think we need a way to specify whether the source data range
>> >> is broadcast/full-range, so perhaps the enum list should be expanded
>> >> to all combinations of BT.601/BT.709 + broadcast/full-range.
>> >
>> >Sounds reasonable. Not that much full range YCbCr stuff out there
>> >perhaps. Well, apart from jpegs I suppose. But no harm in being able
>> >to deal with it.
>> >
>> >>
>> >> (I'm not sure what the canonical naming for broadcast/full-range is,
>> >> we call them narrow and wide)
>> >
>> >We tend to call them full vs. limited range. That's how our
>> >"Broadcast RGB" property is defined as well.
>> >
>>
>> OK, using the same ones sounds sensible.
>>
>> >>
>> >> >And trying to use the same thing for the crtc stuff is probably not
>> >> >going to end well. Like Daniel said we already have the
>> >> >'Broadcast RGB' property muddying the waters there, and that stuff
>> >> >also ties in with what colorspace we signal to the sink via
>> >> >infoframes/whatever the DP thing was called. So my gut feeling is
>> >> >that trying to use the same property everywhere will just end up
>> >> >messy.
>> >>
>> >> Yeah, agreed. If/when someone wants to add CSC on the output of a CRTC
>> >> (after GAMMA), we can add a new property.
>> >>
>> >> That makes me wonder about calling this one SOURCE_YCBCR_TO_RGB_CSC to
>> >> be explicit that it describes the source data. Then we can later add
>> >> SINK_RGB_TO_YCBCR_CSC, and it will be 

Re: DRM Atomic property for color-space conversion

[Ville Syrjälä]

On Tue, Jan 31, 2017 at 03:55:41PM +, Brian Starkey wrote:
> On Tue, Jan 31, 2017 at 05:15:46PM +0200, Ville Syrjälä wrote:
> >On Tue, Jan 31, 2017 at 12:33:29PM +, Brian Starkey wrote:
> >> Hi,
> >>
> >> On Mon, Jan 30, 2017 at 03:35:13PM +0200, Ville Syrjälä wrote:
> >> >On Fri, Jan 27, 2017 at 05:23:24PM +, Brian Starkey wrote:
> >> >> Hi,
> >> >>
> >> >> We're looking to enable the per-plane color management hardware in
> >> >> Mali-DP with atomic properties, which has sparked some conversation
> >> >> around how to handle YCbCr formats.
> >> >>
> >> >> As it stands today, it's assumed that a driver will implicitly "do the
> >> >> right thing" to display a YCbCr buffer.
> >> >>
> >> >> YCbCr data often uses different gamma curves and signal ranges (e.g.
> >> >> BT.609, BT.701, BT.2020, studio range, full-range), so its desirable
> >> >> to be able to explicitly control the YCbCr to RGB conversion process
> >> >> from userspace.
> >> >>
> >> >> We're proposing adding a "CSC" (color-space conversion) property to
> >> >> control this - primarily per-plane for framebuffer->pipeline CSC, but
> >> >> perhaps one per CRTC too for devices which have an RGB pipeline and
> >> >> want to output in YUV to the display:
> >> >>
> >> >> Name: "CSC"
> >> >> Type: ENUM | ATOMIC;
> >> >> Enum values (representative):
> >> >> "default":
> >> >> Same behaviour as now. "Some kind" of YCbCr->RGB conversion
> >> >> for YCbCr buffers, bypass for RGB buffers
> >> >> "disable":
> >> >> Explicitly disable all colorspace conversion (i.e. use an
> >> >> identity matrix).
> >> >> "YCbCr to RGB: BT.709":
> >> >> Only valid for YCbCr formats. CSC in accordance with BT.709
> >> >> using [16..235] for (8-bit) luma values, and [16..240] for
> >> >> 8-bit chroma values. For 10-bit formats, the range limits are
> >> >> multiplied by 4.
> >> >> "YCbCr to RGB: BT.709 full-swing":
> >> >> Only valid for YCbCr formats. CSC in accordance with BT.709,
> >> >> but using the full range of each channel.
> >> >> "YCbCr to RGB: Use CTM":*
> >> >> Only valid for YCbCr formats. Use the matrix applied via the
> >> >> plane's CTM property
> >> >> "RGB to RGB: Use CTM":*
> >> >> Only valid for RGB formats. Use the matrix applied via the
> >> >> plane's CTM property
> >> >> "Use CTM":*
> >> >> Valid for any format. Use the matrix applied via the plane's
> >> >> CTM property
> >> >> ... any other values for BT.601, BT.2020, RGB to YCbCr etc. etc. as
> >> >> they are required.
> >> >
> >> >Having some RGB2RGB and YCBCR2RGB things in the same property seems
> >> >weird. I would just go with something very simple like:
> >> >
> >> >YCBCR_TO_RGB_CSC:
> >> >* BT.601
> >> >* BT.709
> >> >* custom matrix
> >> >
> >>
> >> I think we've agreed in #dri-devel that this CSC property
> >> can't/shouldn't be mapped on-to the existing (hardware implementing
> >> the) CTM property - even in the case of per-plane color management -
> >> because CSC needs to be done before DEGAMMA.
> >>
> >> So, I'm in favour of going with what you suggested in the first place:
> >>
> >> A new YCBCR_TO_RGB_CSC property, enum type, with a list of fixed
> >> conversions. I'd drop the custom matrix for now, as we'd need to add
> >> another property to attach the custom matrix blob too.
> >>
> >> I still think we need a way to specify whether the source data range
> >> is broadcast/full-range, so perhaps the enum list should be expanded
> >> to all combinations of BT.601/BT.709 + broadcast/full-range.
> >
> >Sounds reasonable. Not that much full range YCbCr stuff out there
> >perhaps. Well, apart from jpegs I suppose. But no harm in being able
> >to deal with it.
> >
> >>
> >> (I'm not sure what the canonical naming for broadcast/full-range is,
> >> we call them narrow and wide)
> >
> >We tend to call them full vs. limited range. That's how our
> >"Broadcast RGB" property is defined as well.
> >
> 
> OK, using the same ones sounds sensible.
> 
> >>
> >> >And trying to use the same thing for the crtc stuff is probably not
> >> >going to end well. Like Daniel said we already have the
> >> >'Broadcast RGB' property muddying the waters there, and that stuff
> >> >also ties in with what colorspace we signal to the sink via
> >> >infoframes/whatever the DP thing was called. So my gut feeling is
> >> >that trying to use the same property everywhere will just end up
> >> >messy.
> >>
> >> Yeah, agreed. If/when someone wants to add CSC on the output of a CRTC
> >> (after GAMMA), we can add a new property.
> >>
> >> That makes me wonder about calling this one SOURCE_YCBCR_TO_RGB_CSC to
> >> be explicit that it describes the source data. Then we can later add
> >> SINK_RGB_TO_YCBCR_CSC, and it will be reasonably obvious that its
> >> value describes the output data rather than the input data.
> >
> >Source and sink have a slight connotation in my mind wrt. the box 

Re: DRM Atomic property for color-space conversion

[Ville Syrjälä]

On Tue, Jan 31, 2017 at 03:55:41PM +, Brian Starkey wrote:
> On Tue, Jan 31, 2017 at 05:15:46PM +0200, Ville Syrjälä wrote:
> >On Tue, Jan 31, 2017 at 12:33:29PM +, Brian Starkey wrote:
> >> Hi,
> >>
> >> On Mon, Jan 30, 2017 at 03:35:13PM +0200, Ville Syrjälä wrote:
> >> >On Fri, Jan 27, 2017 at 05:23:24PM +, Brian Starkey wrote:
> >> >> Hi,
> >> >>
> >> >> We're looking to enable the per-plane color management hardware in
> >> >> Mali-DP with atomic properties, which has sparked some conversation
> >> >> around how to handle YCbCr formats.
> >> >>
> >> >> As it stands today, it's assumed that a driver will implicitly "do the
> >> >> right thing" to display a YCbCr buffer.
> >> >>
> >> >> YCbCr data often uses different gamma curves and signal ranges (e.g.
> >> >> BT.609, BT.701, BT.2020, studio range, full-range), so its desirable
> >> >> to be able to explicitly control the YCbCr to RGB conversion process
> >> >> from userspace.
> >> >>
> >> >> We're proposing adding a "CSC" (color-space conversion) property to
> >> >> control this - primarily per-plane for framebuffer->pipeline CSC, but
> >> >> perhaps one per CRTC too for devices which have an RGB pipeline and
> >> >> want to output in YUV to the display:
> >> >>
> >> >> Name: "CSC"
> >> >> Type: ENUM | ATOMIC;
> >> >> Enum values (representative):
> >> >> "default":
> >> >> Same behaviour as now. "Some kind" of YCbCr->RGB conversion
> >> >> for YCbCr buffers, bypass for RGB buffers
> >> >> "disable":
> >> >> Explicitly disable all colorspace conversion (i.e. use an
> >> >> identity matrix).
> >> >> "YCbCr to RGB: BT.709":
> >> >> Only valid for YCbCr formats. CSC in accordance with BT.709
> >> >> using [16..235] for (8-bit) luma values, and [16..240] for
> >> >> 8-bit chroma values. For 10-bit formats, the range limits are
> >> >> multiplied by 4.
> >> >> "YCbCr to RGB: BT.709 full-swing":
> >> >> Only valid for YCbCr formats. CSC in accordance with BT.709,
> >> >> but using the full range of each channel.
> >> >> "YCbCr to RGB: Use CTM":*
> >> >> Only valid for YCbCr formats. Use the matrix applied via the
> >> >> plane's CTM property
> >> >> "RGB to RGB: Use CTM":*
> >> >> Only valid for RGB formats. Use the matrix applied via the
> >> >> plane's CTM property
> >> >> "Use CTM":*
> >> >> Valid for any format. Use the matrix applied via the plane's
> >> >> CTM property
> >> >> ... any other values for BT.601, BT.2020, RGB to YCbCr etc. etc. as
> >> >> they are required.
> >> >
> >> >Having some RGB2RGB and YCBCR2RGB things in the same property seems
> >> >weird. I would just go with something very simple like:
> >> >
> >> >YCBCR_TO_RGB_CSC:
> >> >* BT.601
> >> >* BT.709
> >> >* custom matrix
> >> >
> >>
> >> I think we've agreed in #dri-devel that this CSC property
> >> can't/shouldn't be mapped on-to the existing (hardware implementing
> >> the) CTM property - even in the case of per-plane color management -
> >> because CSC needs to be done before DEGAMMA.
> >>
> >> So, I'm in favour of going with what you suggested in the first place:
> >>
> >> A new YCBCR_TO_RGB_CSC property, enum type, with a list of fixed
> >> conversions. I'd drop the custom matrix for now, as we'd need to add
> >> another property to attach the custom matrix blob too.
> >>
> >> I still think we need a way to specify whether the source data range
> >> is broadcast/full-range, so perhaps the enum list should be expanded
> >> to all combinations of BT.601/BT.709 + broadcast/full-range.
> >
> >Sounds reasonable. Not that much full range YCbCr stuff out there
> >perhaps. Well, apart from jpegs I suppose. But no harm in being able
> >to deal with it.
> >
> >>
> >> (I'm not sure what the canonical naming for broadcast/full-range is,
> >> we call them narrow and wide)
> >
> >We tend to call them full vs. limited range. That's how our
> >"Broadcast RGB" property is defined as well.
> >
> 
> OK, using the same ones sounds sensible.
> 
> >>
> >> >And trying to use the same thing for the crtc stuff is probably not
> >> >going to end well. Like Daniel said we already have the
> >> >'Broadcast RGB' property muddying the waters there, and that stuff
> >> >also ties in with what colorspace we signal to the sink via
> >> >infoframes/whatever the DP thing was called. So my gut feeling is
> >> >that trying to use the same property everywhere will just end up
> >> >messy.
> >>
> >> Yeah, agreed. If/when someone wants to add CSC on the output of a CRTC
> >> (after GAMMA), we can add a new property.
> >>
> >> That makes me wonder about calling this one SOURCE_YCBCR_TO_RGB_CSC to
> >> be explicit that it describes the source data. Then we can later add
> >> SINK_RGB_TO_YCBCR_CSC, and it will be reasonably obvious that its
> >> value describes the output data rather than the input data.
> >
> >Source and sink have a slight connotation in my mind wrt. the box 

Re: DRM Atomic property for color-space conversion

[Brian Starkey]

On Tue, Jan 31, 2017 at 05:15:46PM +0200, Ville Syrjälä wrote:

On Tue, Jan 31, 2017 at 12:33:29PM +, Brian Starkey wrote:

Hi,

On Mon, Jan 30, 2017 at 03:35:13PM +0200, Ville Syrjälä wrote:
>On Fri, Jan 27, 2017 at 05:23:24PM +, Brian Starkey wrote:
>> Hi,
>>
>> We're looking to enable the per-plane color management hardware in
>> Mali-DP with atomic properties, which has sparked some conversation
>> around how to handle YCbCr formats.
>>
>> As it stands today, it's assumed that a driver will implicitly "do the
>> right thing" to display a YCbCr buffer.
>>
>> YCbCr data often uses different gamma curves and signal ranges (e.g.
>> BT.609, BT.701, BT.2020, studio range, full-range), so its desirable
>> to be able to explicitly control the YCbCr to RGB conversion process
>> from userspace.
>>
>> We're proposing adding a "CSC" (color-space conversion) property to
>> control this - primarily per-plane for framebuffer->pipeline CSC, but
>> perhaps one per CRTC too for devices which have an RGB pipeline and
>> want to output in YUV to the display:
>>
>> Name: "CSC"
>> Type: ENUM | ATOMIC;
>> Enum values (representative):
>> "default":
>>Same behaviour as now. "Some kind" of YCbCr->RGB conversion
>>for YCbCr buffers, bypass for RGB buffers
>> "disable":
>>Explicitly disable all colorspace conversion (i.e. use an
>>identity matrix).
>> "YCbCr to RGB: BT.709":
>>Only valid for YCbCr formats. CSC in accordance with BT.709
>>using [16..235] for (8-bit) luma values, and [16..240] for
>>8-bit chroma values. For 10-bit formats, the range limits are
>>multiplied by 4.
>> "YCbCr to RGB: BT.709 full-swing":
>>Only valid for YCbCr formats. CSC in accordance with BT.709,
>>but using the full range of each channel.
>> "YCbCr to RGB: Use CTM":*
>>Only valid for YCbCr formats. Use the matrix applied via the
>>plane's CTM property
>> "RGB to RGB: Use CTM":*
>>Only valid for RGB formats. Use the matrix applied via the
>>plane's CTM property
>> "Use CTM":*
>>Valid for any format. Use the matrix applied via the plane's
>>CTM property
>> ... any other values for BT.601, BT.2020, RGB to YCbCr etc. etc. as
>> they are required.
>
>Having some RGB2RGB and YCBCR2RGB things in the same property seems
>weird. I would just go with something very simple like:
>
>YCBCR_TO_RGB_CSC:
>* BT.601
>* BT.709
>* custom matrix
>

I think we've agreed in #dri-devel that this CSC property
can't/shouldn't be mapped on-to the existing (hardware implementing
the) CTM property - even in the case of per-plane color management -
because CSC needs to be done before DEGAMMA.

So, I'm in favour of going with what you suggested in the first place:

A new YCBCR_TO_RGB_CSC property, enum type, with a list of fixed
conversions. I'd drop the custom matrix for now, as we'd need to add
another property to attach the custom matrix blob too.

I still think we need a way to specify whether the source data range
is broadcast/full-range, so perhaps the enum list should be expanded
to all combinations of BT.601/BT.709 + broadcast/full-range.


Sounds reasonable. Not that much full range YCbCr stuff out there
perhaps. Well, apart from jpegs I suppose. But no harm in being able
to deal with it.



(I'm not sure what the canonical naming for broadcast/full-range is,
we call them narrow and wide)


We tend to call them full vs. limited range. That's how our
"Broadcast RGB" property is defined as well.



OK, using the same ones sounds sensible.



>And trying to use the same thing for the crtc stuff is probably not
>going to end well. Like Daniel said we already have the
>'Broadcast RGB' property muddying the waters there, and that stuff
>also ties in with what colorspace we signal to the sink via
>infoframes/whatever the DP thing was called. So my gut feeling is
>that trying to use the same property everywhere will just end up
>messy.

Yeah, agreed. If/when someone wants to add CSC on the output of a CRTC
(after GAMMA), we can add a new property.

That makes me wonder about calling this one SOURCE_YCBCR_TO_RGB_CSC to
be explicit that it describes the source data. Then we can later add
SINK_RGB_TO_YCBCR_CSC, and it will be reasonably obvious that its
value describes the output data rather than the input data.


Source and sink have a slight connotation in my mind wrt. the box that
produces the display signal and the box that eats the signal. So trying
to use the same terms to describe the internals of the pipeline inside
the "source box" migth lead to some confusion. But we do probably need
some decent names for these to make the layout of the pipeline clear.
Input/output are the other names that popped to my mind but those aren't
necessarily any better. But in the end I think I could live with whatever
names we happen to pick, as long as we document the pipeline clearly.

Long ago I did wonder if we should just start indexing these things

Re: DRM Atomic property for color-space conversion

[Brian Starkey]

On Tue, Jan 31, 2017 at 05:15:46PM +0200, Ville Syrjälä wrote:

On Tue, Jan 31, 2017 at 12:33:29PM +, Brian Starkey wrote:

Hi,

On Mon, Jan 30, 2017 at 03:35:13PM +0200, Ville Syrjälä wrote:
>On Fri, Jan 27, 2017 at 05:23:24PM +, Brian Starkey wrote:
>> Hi,
>>
>> We're looking to enable the per-plane color management hardware in
>> Mali-DP with atomic properties, which has sparked some conversation
>> around how to handle YCbCr formats.
>>
>> As it stands today, it's assumed that a driver will implicitly "do the
>> right thing" to display a YCbCr buffer.
>>
>> YCbCr data often uses different gamma curves and signal ranges (e.g.
>> BT.609, BT.701, BT.2020, studio range, full-range), so its desirable
>> to be able to explicitly control the YCbCr to RGB conversion process
>> from userspace.
>>
>> We're proposing adding a "CSC" (color-space conversion) property to
>> control this - primarily per-plane for framebuffer->pipeline CSC, but
>> perhaps one per CRTC too for devices which have an RGB pipeline and
>> want to output in YUV to the display:
>>
>> Name: "CSC"
>> Type: ENUM | ATOMIC;
>> Enum values (representative):
>> "default":
>>Same behaviour as now. "Some kind" of YCbCr->RGB conversion
>>for YCbCr buffers, bypass for RGB buffers
>> "disable":
>>Explicitly disable all colorspace conversion (i.e. use an
>>identity matrix).
>> "YCbCr to RGB: BT.709":
>>Only valid for YCbCr formats. CSC in accordance with BT.709
>>using [16..235] for (8-bit) luma values, and [16..240] for
>>8-bit chroma values. For 10-bit formats, the range limits are
>>multiplied by 4.
>> "YCbCr to RGB: BT.709 full-swing":
>>Only valid for YCbCr formats. CSC in accordance with BT.709,
>>but using the full range of each channel.
>> "YCbCr to RGB: Use CTM":*
>>Only valid for YCbCr formats. Use the matrix applied via the
>>plane's CTM property
>> "RGB to RGB: Use CTM":*
>>Only valid for RGB formats. Use the matrix applied via the
>>plane's CTM property
>> "Use CTM":*
>>Valid for any format. Use the matrix applied via the plane's
>>CTM property
>> ... any other values for BT.601, BT.2020, RGB to YCbCr etc. etc. as
>> they are required.
>
>Having some RGB2RGB and YCBCR2RGB things in the same property seems
>weird. I would just go with something very simple like:
>
>YCBCR_TO_RGB_CSC:
>* BT.601
>* BT.709
>* custom matrix
>

I think we've agreed in #dri-devel that this CSC property
can't/shouldn't be mapped on-to the existing (hardware implementing
the) CTM property - even in the case of per-plane color management -
because CSC needs to be done before DEGAMMA.

So, I'm in favour of going with what you suggested in the first place:

A new YCBCR_TO_RGB_CSC property, enum type, with a list of fixed
conversions. I'd drop the custom matrix for now, as we'd need to add
another property to attach the custom matrix blob too.

I still think we need a way to specify whether the source data range
is broadcast/full-range, so perhaps the enum list should be expanded
to all combinations of BT.601/BT.709 + broadcast/full-range.


Sounds reasonable. Not that much full range YCbCr stuff out there
perhaps. Well, apart from jpegs I suppose. But no harm in being able
to deal with it.



(I'm not sure what the canonical naming for broadcast/full-range is,
we call them narrow and wide)


We tend to call them full vs. limited range. That's how our
"Broadcast RGB" property is defined as well.



OK, using the same ones sounds sensible.



>And trying to use the same thing for the crtc stuff is probably not
>going to end well. Like Daniel said we already have the
>'Broadcast RGB' property muddying the waters there, and that stuff
>also ties in with what colorspace we signal to the sink via
>infoframes/whatever the DP thing was called. So my gut feeling is
>that trying to use the same property everywhere will just end up
>messy.

Yeah, agreed. If/when someone wants to add CSC on the output of a CRTC
(after GAMMA), we can add a new property.

That makes me wonder about calling this one SOURCE_YCBCR_TO_RGB_CSC to
be explicit that it describes the source data. Then we can later add
SINK_RGB_TO_YCBCR_CSC, and it will be reasonably obvious that its
value describes the output data rather than the input data.


Source and sink have a slight connotation in my mind wrt. the box that
produces the display signal and the box that eats the signal. So trying
to use the same terms to describe the internals of the pipeline inside
the "source box" migth lead to some confusion. But we do probably need
some decent names for these to make the layout of the pipeline clear.
Input/output are the other names that popped to my mind but those aren't
necessarily any better. But in the end I think I could live with whatever
names we happen to pick, as long as we document the pipeline clearly.

Long ago I did wonder if we should just start indexing these things

Re: DRM Atomic property for color-space conversion

[Ville Syrjälä]

On Tue, Jan 31, 2017 at 12:33:29PM +, Brian Starkey wrote:
> Hi,
> 
> On Mon, Jan 30, 2017 at 03:35:13PM +0200, Ville Syrjälä wrote:
> >On Fri, Jan 27, 2017 at 05:23:24PM +, Brian Starkey wrote:
> >> Hi,
> >>
> >> We're looking to enable the per-plane color management hardware in
> >> Mali-DP with atomic properties, which has sparked some conversation
> >> around how to handle YCbCr formats.
> >>
> >> As it stands today, it's assumed that a driver will implicitly "do the
> >> right thing" to display a YCbCr buffer.
> >>
> >> YCbCr data often uses different gamma curves and signal ranges (e.g.
> >> BT.609, BT.701, BT.2020, studio range, full-range), so its desirable
> >> to be able to explicitly control the YCbCr to RGB conversion process
> >> from userspace.
> >>
> >> We're proposing adding a "CSC" (color-space conversion) property to
> >> control this - primarily per-plane for framebuffer->pipeline CSC, but
> >> perhaps one per CRTC too for devices which have an RGB pipeline and
> >> want to output in YUV to the display:
> >>
> >> Name: "CSC"
> >> Type: ENUM | ATOMIC;
> >> Enum values (representative):
> >> "default":
> >>Same behaviour as now. "Some kind" of YCbCr->RGB conversion
> >>for YCbCr buffers, bypass for RGB buffers
> >> "disable":
> >>Explicitly disable all colorspace conversion (i.e. use an
> >>identity matrix).
> >> "YCbCr to RGB: BT.709":
> >>Only valid for YCbCr formats. CSC in accordance with BT.709
> >>using [16..235] for (8-bit) luma values, and [16..240] for
> >>8-bit chroma values. For 10-bit formats, the range limits are
> >>multiplied by 4.
> >> "YCbCr to RGB: BT.709 full-swing":
> >>Only valid for YCbCr formats. CSC in accordance with BT.709,
> >>but using the full range of each channel.
> >> "YCbCr to RGB: Use CTM":*
> >>Only valid for YCbCr formats. Use the matrix applied via the
> >>plane's CTM property
> >> "RGB to RGB: Use CTM":*
> >>Only valid for RGB formats. Use the matrix applied via the
> >>plane's CTM property
> >> "Use CTM":*
> >>Valid for any format. Use the matrix applied via the plane's
> >>CTM property
> >> ... any other values for BT.601, BT.2020, RGB to YCbCr etc. etc. as
> >> they are required.
> >
> >Having some RGB2RGB and YCBCR2RGB things in the same property seems
> >weird. I would just go with something very simple like:
> >
> >YCBCR_TO_RGB_CSC:
> >* BT.601
> >* BT.709
> >* custom matrix
> >
> 
> I think we've agreed in #dri-devel that this CSC property
> can't/shouldn't be mapped on-to the existing (hardware implementing
> the) CTM property - even in the case of per-plane color management -
> because CSC needs to be done before DEGAMMA.
> 
> So, I'm in favour of going with what you suggested in the first place:
> 
> A new YCBCR_TO_RGB_CSC property, enum type, with a list of fixed
> conversions. I'd drop the custom matrix for now, as we'd need to add
> another property to attach the custom matrix blob too.
> 
> I still think we need a way to specify whether the source data range
> is broadcast/full-range, so perhaps the enum list should be expanded
> to all combinations of BT.601/BT.709 + broadcast/full-range.

Sounds reasonable. Not that much full range YCbCr stuff out there
perhaps. Well, apart from jpegs I suppose. But no harm in being able
to deal with it.

> 
> (I'm not sure what the canonical naming for broadcast/full-range is,
> we call them narrow and wide)

We tend to call them full vs. limited range. That's how our
"Broadcast RGB" property is defined as well.

> 
> >And trying to use the same thing for the crtc stuff is probably not
> >going to end well. Like Daniel said we already have the
> >'Broadcast RGB' property muddying the waters there, and that stuff
> >also ties in with what colorspace we signal to the sink via
> >infoframes/whatever the DP thing was called. So my gut feeling is
> >that trying to use the same property everywhere will just end up
> >messy.
> 
> Yeah, agreed. If/when someone wants to add CSC on the output of a CRTC
> (after GAMMA), we can add a new property.
> 
> That makes me wonder about calling this one SOURCE_YCBCR_TO_RGB_CSC to
> be explicit that it describes the source data. Then we can later add
> SINK_RGB_TO_YCBCR_CSC, and it will be reasonably obvious that its
> value describes the output data rather than the input data.

Source and sink have a slight connotation in my mind wrt. the box that
produces the display signal and the box that eats the signal. So trying
to use the same terms to describe the internals of the pipeline inside
the "source box" migth lead to some confusion. But we do probably need
some decent names for these to make the layout of the pipeline clear.
Input/output are the other names that popped to my mind but those aren't
necessarily any better. But in the end I think I could live with whatever
names we happen to pick, as long as we document the pipeline clearly.

Long ago I did wonder if we should just start indexing these 

Re: DRM Atomic property for color-space conversion

[Ville Syrjälä]

On Tue, Jan 31, 2017 at 12:33:29PM +, Brian Starkey wrote:
> Hi,
> 
> On Mon, Jan 30, 2017 at 03:35:13PM +0200, Ville Syrjälä wrote:
> >On Fri, Jan 27, 2017 at 05:23:24PM +, Brian Starkey wrote:
> >> Hi,
> >>
> >> We're looking to enable the per-plane color management hardware in
> >> Mali-DP with atomic properties, which has sparked some conversation
> >> around how to handle YCbCr formats.
> >>
> >> As it stands today, it's assumed that a driver will implicitly "do the
> >> right thing" to display a YCbCr buffer.
> >>
> >> YCbCr data often uses different gamma curves and signal ranges (e.g.
> >> BT.609, BT.701, BT.2020, studio range, full-range), so its desirable
> >> to be able to explicitly control the YCbCr to RGB conversion process
> >> from userspace.
> >>
> >> We're proposing adding a "CSC" (color-space conversion) property to
> >> control this - primarily per-plane for framebuffer->pipeline CSC, but
> >> perhaps one per CRTC too for devices which have an RGB pipeline and
> >> want to output in YUV to the display:
> >>
> >> Name: "CSC"
> >> Type: ENUM | ATOMIC;
> >> Enum values (representative):
> >> "default":
> >>Same behaviour as now. "Some kind" of YCbCr->RGB conversion
> >>for YCbCr buffers, bypass for RGB buffers
> >> "disable":
> >>Explicitly disable all colorspace conversion (i.e. use an
> >>identity matrix).
> >> "YCbCr to RGB: BT.709":
> >>Only valid for YCbCr formats. CSC in accordance with BT.709
> >>using [16..235] for (8-bit) luma values, and [16..240] for
> >>8-bit chroma values. For 10-bit formats, the range limits are
> >>multiplied by 4.
> >> "YCbCr to RGB: BT.709 full-swing":
> >>Only valid for YCbCr formats. CSC in accordance with BT.709,
> >>but using the full range of each channel.
> >> "YCbCr to RGB: Use CTM":*
> >>Only valid for YCbCr formats. Use the matrix applied via the
> >>plane's CTM property
> >> "RGB to RGB: Use CTM":*
> >>Only valid for RGB formats. Use the matrix applied via the
> >>plane's CTM property
> >> "Use CTM":*
> >>Valid for any format. Use the matrix applied via the plane's
> >>CTM property
> >> ... any other values for BT.601, BT.2020, RGB to YCbCr etc. etc. as
> >> they are required.
> >
> >Having some RGB2RGB and YCBCR2RGB things in the same property seems
> >weird. I would just go with something very simple like:
> >
> >YCBCR_TO_RGB_CSC:
> >* BT.601
> >* BT.709
> >* custom matrix
> >
> 
> I think we've agreed in #dri-devel that this CSC property
> can't/shouldn't be mapped on-to the existing (hardware implementing
> the) CTM property - even in the case of per-plane color management -
> because CSC needs to be done before DEGAMMA.
> 
> So, I'm in favour of going with what you suggested in the first place:
> 
> A new YCBCR_TO_RGB_CSC property, enum type, with a list of fixed
> conversions. I'd drop the custom matrix for now, as we'd need to add
> another property to attach the custom matrix blob too.
> 
> I still think we need a way to specify whether the source data range
> is broadcast/full-range, so perhaps the enum list should be expanded
> to all combinations of BT.601/BT.709 + broadcast/full-range.

Sounds reasonable. Not that much full range YCbCr stuff out there
perhaps. Well, apart from jpegs I suppose. But no harm in being able
to deal with it.

> 
> (I'm not sure what the canonical naming for broadcast/full-range is,
> we call them narrow and wide)

We tend to call them full vs. limited range. That's how our
"Broadcast RGB" property is defined as well.

> 
> >And trying to use the same thing for the crtc stuff is probably not
> >going to end well. Like Daniel said we already have the
> >'Broadcast RGB' property muddying the waters there, and that stuff
> >also ties in with what colorspace we signal to the sink via
> >infoframes/whatever the DP thing was called. So my gut feeling is
> >that trying to use the same property everywhere will just end up
> >messy.
> 
> Yeah, agreed. If/when someone wants to add CSC on the output of a CRTC
> (after GAMMA), we can add a new property.
> 
> That makes me wonder about calling this one SOURCE_YCBCR_TO_RGB_CSC to
> be explicit that it describes the source data. Then we can later add
> SINK_RGB_TO_YCBCR_CSC, and it will be reasonably obvious that its
> value describes the output data rather than the input data.

Source and sink have a slight connotation in my mind wrt. the box that
produces the display signal and the box that eats the signal. So trying
to use the same terms to describe the internals of the pipeline inside
the "source box" migth lead to some confusion. But we do probably need
some decent names for these to make the layout of the pipeline clear.
Input/output are the other names that popped to my mind but those aren't
necessarily any better. But in the end I think I could live with whatever
names we happen to pick, as long as we document the pipeline clearly.

Long ago I did wonder if we should just start indexing these 

Re: DRM Atomic property for color-space conversion

[Brian Starkey]

Hi,

On Mon, Jan 30, 2017 at 03:35:13PM +0200, Ville Syrjälä wrote:

On Fri, Jan 27, 2017 at 05:23:24PM +, Brian Starkey wrote:

Hi,

We're looking to enable the per-plane color management hardware in
Mali-DP with atomic properties, which has sparked some conversation
around how to handle YCbCr formats.

As it stands today, it's assumed that a driver will implicitly "do the
right thing" to display a YCbCr buffer.

YCbCr data often uses different gamma curves and signal ranges (e.g.
BT.609, BT.701, BT.2020, studio range, full-range), so its desirable
to be able to explicitly control the YCbCr to RGB conversion process
from userspace.

We're proposing adding a "CSC" (color-space conversion) property to
control this - primarily per-plane for framebuffer->pipeline CSC, but
perhaps one per CRTC too for devices which have an RGB pipeline and
want to output in YUV to the display:

Name: "CSC"
Type: ENUM | ATOMIC;
Enum values (representative):
"default":
Same behaviour as now. "Some kind" of YCbCr->RGB conversion
for YCbCr buffers, bypass for RGB buffers
"disable":
Explicitly disable all colorspace conversion (i.e. use an
identity matrix).
"YCbCr to RGB: BT.709":
Only valid for YCbCr formats. CSC in accordance with BT.709
using [16..235] for (8-bit) luma values, and [16..240] for
8-bit chroma values. For 10-bit formats, the range limits are
multiplied by 4.
"YCbCr to RGB: BT.709 full-swing":
Only valid for YCbCr formats. CSC in accordance with BT.709,
but using the full range of each channel.
"YCbCr to RGB: Use CTM":*
Only valid for YCbCr formats. Use the matrix applied via the
plane's CTM property
"RGB to RGB: Use CTM":*
Only valid for RGB formats. Use the matrix applied via the
plane's CTM property
"Use CTM":*
Valid for any format. Use the matrix applied via the plane's
CTM property
... any other values for BT.601, BT.2020, RGB to YCbCr etc. etc. as
they are required.


Having some RGB2RGB and YCBCR2RGB things in the same property seems
weird. I would just go with something very simple like:

YCBCR_TO_RGB_CSC:
* BT.601
* BT.709
* custom matrix



I think we've agreed in #dri-devel that this CSC property
can't/shouldn't be mapped on-to the existing (hardware implementing
the) CTM property - even in the case of per-plane color management -
because CSC needs to be done before DEGAMMA.

So, I'm in favour of going with what you suggested in the first place:

A new YCBCR_TO_RGB_CSC property, enum type, with a list of fixed
conversions. I'd drop the custom matrix for now, as we'd need to add
another property to attach the custom matrix blob too.

I still think we need a way to specify whether the source data range
is broadcast/full-range, so perhaps the enum list should be expanded
to all combinations of BT.601/BT.709 + broadcast/full-range.

(I'm not sure what the canonical naming for broadcast/full-range is,
we call them narrow and wide)


And trying to use the same thing for the crtc stuff is probably not
going to end well. Like Daniel said we already have the
'Broadcast RGB' property muddying the waters there, and that stuff
also ties in with what colorspace we signal to the sink via
infoframes/whatever the DP thing was called. So my gut feeling is
that trying to use the same property everywhere will just end up
messy.


Yeah, agreed. If/when someone wants to add CSC on the output of a CRTC
(after GAMMA), we can add a new property.

That makes me wonder about calling this one SOURCE_YCBCR_TO_RGB_CSC to
be explicit that it describes the source data. Then we can later add
SINK_RGB_TO_YCBCR_CSC, and it will be reasonably obvious that its
value describes the output data rather than the input data.

I want to avoid confusion caused by ending up with two
{CS}_TO_{CS}_CSC properties, where one is describing the data to the
left of it, and the other describing the data to the right of it, with
no real way of telling which way around it is.

Cheers,
Brian



--
Ville Syrjälä
Intel OTC

Re: DRM Atomic property for color-space conversion

[Brian Starkey]

Hi,

On Mon, Jan 30, 2017 at 03:35:13PM +0200, Ville Syrjälä wrote:

On Fri, Jan 27, 2017 at 05:23:24PM +, Brian Starkey wrote:

Hi,

We're looking to enable the per-plane color management hardware in
Mali-DP with atomic properties, which has sparked some conversation
around how to handle YCbCr formats.

As it stands today, it's assumed that a driver will implicitly "do the
right thing" to display a YCbCr buffer.

YCbCr data often uses different gamma curves and signal ranges (e.g.
BT.609, BT.701, BT.2020, studio range, full-range), so its desirable
to be able to explicitly control the YCbCr to RGB conversion process
from userspace.

We're proposing adding a "CSC" (color-space conversion) property to
control this - primarily per-plane for framebuffer->pipeline CSC, but
perhaps one per CRTC too for devices which have an RGB pipeline and
want to output in YUV to the display:

Name: "CSC"
Type: ENUM | ATOMIC;
Enum values (representative):
"default":
Same behaviour as now. "Some kind" of YCbCr->RGB conversion
for YCbCr buffers, bypass for RGB buffers
"disable":
Explicitly disable all colorspace conversion (i.e. use an
identity matrix).
"YCbCr to RGB: BT.709":
Only valid for YCbCr formats. CSC in accordance with BT.709
using [16..235] for (8-bit) luma values, and [16..240] for
8-bit chroma values. For 10-bit formats, the range limits are
multiplied by 4.
"YCbCr to RGB: BT.709 full-swing":
Only valid for YCbCr formats. CSC in accordance with BT.709,
but using the full range of each channel.
"YCbCr to RGB: Use CTM":*
Only valid for YCbCr formats. Use the matrix applied via the
plane's CTM property
"RGB to RGB: Use CTM":*
Only valid for RGB formats. Use the matrix applied via the
plane's CTM property
"Use CTM":*
Valid for any format. Use the matrix applied via the plane's
CTM property
... any other values for BT.601, BT.2020, RGB to YCbCr etc. etc. as
they are required.


Having some RGB2RGB and YCBCR2RGB things in the same property seems
weird. I would just go with something very simple like:

YCBCR_TO_RGB_CSC:
* BT.601
* BT.709
* custom matrix



I think we've agreed in #dri-devel that this CSC property
can't/shouldn't be mapped on-to the existing (hardware implementing
the) CTM property - even in the case of per-plane color management -
because CSC needs to be done before DEGAMMA.

So, I'm in favour of going with what you suggested in the first place:

A new YCBCR_TO_RGB_CSC property, enum type, with a list of fixed
conversions. I'd drop the custom matrix for now, as we'd need to add
another property to attach the custom matrix blob too.

I still think we need a way to specify whether the source data range
is broadcast/full-range, so perhaps the enum list should be expanded
to all combinations of BT.601/BT.709 + broadcast/full-range.

(I'm not sure what the canonical naming for broadcast/full-range is,
we call them narrow and wide)


And trying to use the same thing for the crtc stuff is probably not
going to end well. Like Daniel said we already have the
'Broadcast RGB' property muddying the waters there, and that stuff
also ties in with what colorspace we signal to the sink via
infoframes/whatever the DP thing was called. So my gut feeling is
that trying to use the same property everywhere will just end up
messy.


Yeah, agreed. If/when someone wants to add CSC on the output of a CRTC
(after GAMMA), we can add a new property.

That makes me wonder about calling this one SOURCE_YCBCR_TO_RGB_CSC to
be explicit that it describes the source data. Then we can later add
SINK_RGB_TO_YCBCR_CSC, and it will be reasonably obvious that its
value describes the output data rather than the input data.

I want to avoid confusion caused by ending up with two
{CS}_TO_{CS}_CSC properties, where one is describing the data to the
left of it, and the other describing the data to the right of it, with
no real way of telling which way around it is.

Cheers,
Brian



--
Ville Syrjälä
Intel OTC

Re: DRM Atomic property for color-space conversion

[Ville Syrjälä]

On Fri, Jan 27, 2017 at 05:23:24PM +, Brian Starkey wrote:
> Hi,
> 
> We're looking to enable the per-plane color management hardware in
> Mali-DP with atomic properties, which has sparked some conversation
> around how to handle YCbCr formats.
> 
> As it stands today, it's assumed that a driver will implicitly "do the
> right thing" to display a YCbCr buffer.
> 
> YCbCr data often uses different gamma curves and signal ranges (e.g.
> BT.609, BT.701, BT.2020, studio range, full-range), so its desirable
> to be able to explicitly control the YCbCr to RGB conversion process
> from userspace.
> 
> We're proposing adding a "CSC" (color-space conversion) property to
> control this - primarily per-plane for framebuffer->pipeline CSC, but
> perhaps one per CRTC too for devices which have an RGB pipeline and
> want to output in YUV to the display:
> 
> Name: "CSC"
> Type: ENUM | ATOMIC;
> Enum values (representative):
> "default":
>   Same behaviour as now. "Some kind" of YCbCr->RGB conversion
>   for YCbCr buffers, bypass for RGB buffers
> "disable":
>   Explicitly disable all colorspace conversion (i.e. use an
>   identity matrix).
> "YCbCr to RGB: BT.709":
>   Only valid for YCbCr formats. CSC in accordance with BT.709
>   using [16..235] for (8-bit) luma values, and [16..240] for
>   8-bit chroma values. For 10-bit formats, the range limits are
>   multiplied by 4.
> "YCbCr to RGB: BT.709 full-swing":
>   Only valid for YCbCr formats. CSC in accordance with BT.709,
>   but using the full range of each channel.
> "YCbCr to RGB: Use CTM":*
>   Only valid for YCbCr formats. Use the matrix applied via the
>   plane's CTM property
> "RGB to RGB: Use CTM":*
>   Only valid for RGB formats. Use the matrix applied via the
>   plane's CTM property
> "Use CTM":*
>   Valid for any format. Use the matrix applied via the plane's
>   CTM property
> ... any other values for BT.601, BT.2020, RGB to YCbCr etc. etc. as
> they are required.

Having some RGB2RGB and YCBCR2RGB things in the same property seems
weird. I would just go with something very simple like:

YCBCR_TO_RGB_CSC:
* BT.601
* BT.709
* custom matrix

And trying to use the same thing for the crtc stuff is probably not
going to end well. Like Daniel said we already have the
'Broadcast RGB' property muddying the waters there, and that stuff
also ties in with what colorspace we signal to the sink via
infoframes/whatever the DP thing was called. So my gut feeling is
that trying to use the same property everywhere will just end up
messy.

-- 
Ville Syrjälä
Intel OTC

Re: DRM Atomic property for color-space conversion

[Ville Syrjälä]

On Fri, Jan 27, 2017 at 05:23:24PM +, Brian Starkey wrote:
> Hi,
> 
> We're looking to enable the per-plane color management hardware in
> Mali-DP with atomic properties, which has sparked some conversation
> around how to handle YCbCr formats.
> 
> As it stands today, it's assumed that a driver will implicitly "do the
> right thing" to display a YCbCr buffer.
> 
> YCbCr data often uses different gamma curves and signal ranges (e.g.
> BT.609, BT.701, BT.2020, studio range, full-range), so its desirable
> to be able to explicitly control the YCbCr to RGB conversion process
> from userspace.
> 
> We're proposing adding a "CSC" (color-space conversion) property to
> control this - primarily per-plane for framebuffer->pipeline CSC, but
> perhaps one per CRTC too for devices which have an RGB pipeline and
> want to output in YUV to the display:
> 
> Name: "CSC"
> Type: ENUM | ATOMIC;
> Enum values (representative):
> "default":
>   Same behaviour as now. "Some kind" of YCbCr->RGB conversion
>   for YCbCr buffers, bypass for RGB buffers
> "disable":
>   Explicitly disable all colorspace conversion (i.e. use an
>   identity matrix).
> "YCbCr to RGB: BT.709":
>   Only valid for YCbCr formats. CSC in accordance with BT.709
>   using [16..235] for (8-bit) luma values, and [16..240] for
>   8-bit chroma values. For 10-bit formats, the range limits are
>   multiplied by 4.
> "YCbCr to RGB: BT.709 full-swing":
>   Only valid for YCbCr formats. CSC in accordance with BT.709,
>   but using the full range of each channel.
> "YCbCr to RGB: Use CTM":*
>   Only valid for YCbCr formats. Use the matrix applied via the
>   plane's CTM property
> "RGB to RGB: Use CTM":*
>   Only valid for RGB formats. Use the matrix applied via the
>   plane's CTM property
> "Use CTM":*
>   Valid for any format. Use the matrix applied via the plane's
>   CTM property
> ... any other values for BT.601, BT.2020, RGB to YCbCr etc. etc. as
> they are required.

Having some RGB2RGB and YCBCR2RGB things in the same property seems
weird. I would just go with something very simple like:

YCBCR_TO_RGB_CSC:
* BT.601
* BT.709
* custom matrix

And trying to use the same thing for the crtc stuff is probably not
going to end well. Like Daniel said we already have the
'Broadcast RGB' property muddying the waters there, and that stuff
also ties in with what colorspace we signal to the sink via
infoframes/whatever the DP thing was called. So my gut feeling is
that trying to use the same property everywhere will just end up
messy.

-- 
Ville Syrjälä
Intel OTC

Re: DRM Atomic property for color-space conversion

[Daniel Vetter]

On Fri, Jan 27, 2017 at 05:23:24PM +, Brian Starkey wrote:
> Hi,
> 
> We're looking to enable the per-plane color management hardware in
> Mali-DP with atomic properties, which has sparked some conversation
> around how to handle YCbCr formats.
> 
> As it stands today, it's assumed that a driver will implicitly "do the
> right thing" to display a YCbCr buffer.
> 
> YCbCr data often uses different gamma curves and signal ranges (e.g.
> BT.609, BT.701, BT.2020, studio range, full-range), so its desirable
> to be able to explicitly control the YCbCr to RGB conversion process
> from userspace.
> 
> We're proposing adding a "CSC" (color-space conversion) property to
> control this - primarily per-plane for framebuffer->pipeline CSC, but
> perhaps one per CRTC too for devices which have an RGB pipeline and
> want to output in YUV to the display:
> 
> Name: "CSC"
> Type: ENUM | ATOMIC;
> Enum values (representative):
> "default":
>   Same behaviour as now. "Some kind" of YCbCr->RGB conversion
>   for YCbCr buffers, bypass for RGB buffers
> "disable":
>   Explicitly disable all colorspace conversion (i.e. use an
>   identity matrix).
> "YCbCr to RGB: BT.709":
>   Only valid for YCbCr formats. CSC in accordance with BT.709
>   using [16..235] for (8-bit) luma values, and [16..240] for
>   8-bit chroma values. For 10-bit formats, the range limits are
>   multiplied by 4.
> "YCbCr to RGB: BT.709 full-swing":
>   Only valid for YCbCr formats. CSC in accordance with BT.709,
>   but using the full range of each channel.

We already have a standardized property for broadcast vs. full range. So
needs to be taken out of this one here to avoid silly interactions. It's
not yet atomic-ified though (i.e. not tracked in drm_connector_state).
It's a bit annoying since it's on the connector, but with sufficient glue
we can fix this.

Your helper should probably take that into account too.

> "YCbCr to RGB: Use CTM":*
>   Only valid for YCbCr formats. Use the matrix applied via the
>   plane's CTM property
> "RGB to RGB: Use CTM":*
>   Only valid for RGB formats. Use the matrix applied via the
>   plane's CTM property
> "Use CTM":*
>   Valid for any format. Use the matrix applied via the plane's
>   CTM property
> ... any other values for BT.601, BT.2020, RGB to YCbCr etc. etc. as
> they are required.
> 
> *This assumes color-management is enabled per-plane. We're currently
> working on patches to add this mostly to be able to use per-plane
> degamma, but it would be analogous to the CRTC color-management code
> and so also be able to expose a per-plane CTM property.
> 
> Our hardware implements the color-space conversion as a 3x3 matrix, so
> we can implement a helper to convert a CSC enum value to a CTM matrix
> for use by any hardware which has a programmable CSC matrix. For any
> other hardware, the driver simply needs to map the enum value to
> whatever selector bits are available.
> 
> It's expected that the "Use CTM" value(s) are *not* the common case,
> and most of the time userspace will use one of the provided "standard"
> enum values. The three different flavours of "Use CTM" allow us to
> support hardware whose CSC hardware can only be used on e.g. YCbCr
> data.
> 
> Drivers can of course filter the enum list to expose whichever subset
> the hardware can support.
> 
> Having thrashed this out a bit on IRC with Ville, I think the above
> approach is flexible enough to support at least Mali-DP and i915,
> without burdening userspace any more than necessary. It also provides
> the "default" behaviour which is backwards compatible, and allows for
> fully custom CSC matrices where that is supported.
> 
> We can obviously implement this as a Mali-DP driver private property,
> but it would be good to come up with something to go into the core if
> possible.

It needs userspace either way :-) And I think the tricky bit here is
interaction with the CTM stuff we already have, i.e. what happens when
userspace sets both this and the CTM? Would our helper need to be able to
merge the explicit CTM with the implicit one here with some matrix
multiplication? If we go with "kernel multiplies them" then we could
simplify things a lot I think, since all we'd need is just "none, BT.709,
BT.601, ..." and none of the special values that define interactions with
the CTM.

Or we just chicken out for now and say you can't have a per-plane CTM if
you expose this :-) Since there's no per-plane CTM userspace yet, this is
probably the simplest option ...
-Daniel

> 
> I'd be happy to hear any feedback,
> 
> Thanks,
> Brian
> ___
> dri-devel mailing list
> dri-de...@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

Re: DRM Atomic property for color-space conversion

[Daniel Vetter]

On Fri, Jan 27, 2017 at 05:23:24PM +, Brian Starkey wrote:
> Hi,
> 
> We're looking to enable the per-plane color management hardware in
> Mali-DP with atomic properties, which has sparked some conversation
> around how to handle YCbCr formats.
> 
> As it stands today, it's assumed that a driver will implicitly "do the
> right thing" to display a YCbCr buffer.
> 
> YCbCr data often uses different gamma curves and signal ranges (e.g.
> BT.609, BT.701, BT.2020, studio range, full-range), so its desirable
> to be able to explicitly control the YCbCr to RGB conversion process
> from userspace.
> 
> We're proposing adding a "CSC" (color-space conversion) property to
> control this - primarily per-plane for framebuffer->pipeline CSC, but
> perhaps one per CRTC too for devices which have an RGB pipeline and
> want to output in YUV to the display:
> 
> Name: "CSC"
> Type: ENUM | ATOMIC;
> Enum values (representative):
> "default":
>   Same behaviour as now. "Some kind" of YCbCr->RGB conversion
>   for YCbCr buffers, bypass for RGB buffers
> "disable":
>   Explicitly disable all colorspace conversion (i.e. use an
>   identity matrix).
> "YCbCr to RGB: BT.709":
>   Only valid for YCbCr formats. CSC in accordance with BT.709
>   using [16..235] for (8-bit) luma values, and [16..240] for
>   8-bit chroma values. For 10-bit formats, the range limits are
>   multiplied by 4.
> "YCbCr to RGB: BT.709 full-swing":
>   Only valid for YCbCr formats. CSC in accordance with BT.709,
>   but using the full range of each channel.

We already have a standardized property for broadcast vs. full range. So
needs to be taken out of this one here to avoid silly interactions. It's
not yet atomic-ified though (i.e. not tracked in drm_connector_state).
It's a bit annoying since it's on the connector, but with sufficient glue
we can fix this.

Your helper should probably take that into account too.

> "YCbCr to RGB: Use CTM":*
>   Only valid for YCbCr formats. Use the matrix applied via the
>   plane's CTM property
> "RGB to RGB: Use CTM":*
>   Only valid for RGB formats. Use the matrix applied via the
>   plane's CTM property
> "Use CTM":*
>   Valid for any format. Use the matrix applied via the plane's
>   CTM property
> ... any other values for BT.601, BT.2020, RGB to YCbCr etc. etc. as
> they are required.
> 
> *This assumes color-management is enabled per-plane. We're currently
> working on patches to add this mostly to be able to use per-plane
> degamma, but it would be analogous to the CRTC color-management code
> and so also be able to expose a per-plane CTM property.
> 
> Our hardware implements the color-space conversion as a 3x3 matrix, so
> we can implement a helper to convert a CSC enum value to a CTM matrix
> for use by any hardware which has a programmable CSC matrix. For any
> other hardware, the driver simply needs to map the enum value to
> whatever selector bits are available.
> 
> It's expected that the "Use CTM" value(s) are *not* the common case,
> and most of the time userspace will use one of the provided "standard"
> enum values. The three different flavours of "Use CTM" allow us to
> support hardware whose CSC hardware can only be used on e.g. YCbCr
> data.
> 
> Drivers can of course filter the enum list to expose whichever subset
> the hardware can support.
> 
> Having thrashed this out a bit on IRC with Ville, I think the above
> approach is flexible enough to support at least Mali-DP and i915,
> without burdening userspace any more than necessary. It also provides
> the "default" behaviour which is backwards compatible, and allows for
> fully custom CSC matrices where that is supported.
> 
> We can obviously implement this as a Mali-DP driver private property,
> but it would be good to come up with something to go into the core if
> possible.

It needs userspace either way :-) And I think the tricky bit here is
interaction with the CTM stuff we already have, i.e. what happens when
userspace sets both this and the CTM? Would our helper need to be able to
merge the explicit CTM with the implicit one here with some matrix
multiplication? If we go with "kernel multiplies them" then we could
simplify things a lot I think, since all we'd need is just "none, BT.709,
BT.601, ..." and none of the special values that define interactions with
the CTM.

Or we just chicken out for now and say you can't have a per-plane CTM if
you expose this :-) Since there's no per-plane CTM userspace yet, this is
probably the simplest option ...
-Daniel

> 
> I'd be happy to hear any feedback,
> 
> Thanks,
> Brian
> ___
> dri-devel mailing list
> dri-de...@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

DRM Atomic property for color-space conversion

[Brian Starkey]

Hi,

We're looking to enable the per-plane color management hardware in
Mali-DP with atomic properties, which has sparked some conversation
around how to handle YCbCr formats.

As it stands today, it's assumed that a driver will implicitly "do the
right thing" to display a YCbCr buffer.

YCbCr data often uses different gamma curves and signal ranges (e.g.
BT.609, BT.701, BT.2020, studio range, full-range), so its desirable
to be able to explicitly control the YCbCr to RGB conversion process
from userspace.

We're proposing adding a "CSC" (color-space conversion) property to
control this - primarily per-plane for framebuffer->pipeline CSC, but
perhaps one per CRTC too for devices which have an RGB pipeline and
want to output in YUV to the display:

Name: "CSC"
Type: ENUM | ATOMIC;
Enum values (representative):
"default":
Same behaviour as now. "Some kind" of YCbCr->RGB conversion
for YCbCr buffers, bypass for RGB buffers
"disable":
Explicitly disable all colorspace conversion (i.e. use an
identity matrix).
"YCbCr to RGB: BT.709":
Only valid for YCbCr formats. CSC in accordance with BT.709
using [16..235] for (8-bit) luma values, and [16..240] for
8-bit chroma values. For 10-bit formats, the range limits are
multiplied by 4.
"YCbCr to RGB: BT.709 full-swing":
Only valid for YCbCr formats. CSC in accordance with BT.709,
but using the full range of each channel.
"YCbCr to RGB: Use CTM":*
Only valid for YCbCr formats. Use the matrix applied via the
plane's CTM property
"RGB to RGB: Use CTM":*
Only valid for RGB formats. Use the matrix applied via the
plane's CTM property
"Use CTM":*
Valid for any format. Use the matrix applied via the plane's
CTM property
... any other values for BT.601, BT.2020, RGB to YCbCr etc. etc. as
they are required.

*This assumes color-management is enabled per-plane. We're currently
working on patches to add this mostly to be able to use per-plane
degamma, but it would be analogous to the CRTC color-management code
and so also be able to expose a per-plane CTM property.

Our hardware implements the color-space conversion as a 3x3 matrix, so
we can implement a helper to convert a CSC enum value to a CTM matrix
for use by any hardware which has a programmable CSC matrix. For any
other hardware, the driver simply needs to map the enum value to
whatever selector bits are available.

It's expected that the "Use CTM" value(s) are *not* the common case,
and most of the time userspace will use one of the provided "standard"
enum values. The three different flavours of "Use CTM" allow us to
support hardware whose CSC hardware can only be used on e.g. YCbCr
data.

Drivers can of course filter the enum list to expose whichever subset
the hardware can support.

Having thrashed this out a bit on IRC with Ville, I think the above
approach is flexible enough to support at least Mali-DP and i915,
without burdening userspace any more than necessary. It also provides
the "default" behaviour which is backwards compatible, and allows for
fully custom CSC matrices where that is supported.

We can obviously implement this as a Mali-DP driver private property,
but it would be good to come up with something to go into the core if
possible.

I'd be happy to hear any feedback,

Thanks,
Brian

DRM Atomic property for color-space conversion

[Brian Starkey]

Hi,

We're looking to enable the per-plane color management hardware in
Mali-DP with atomic properties, which has sparked some conversation
around how to handle YCbCr formats.

As it stands today, it's assumed that a driver will implicitly "do the
right thing" to display a YCbCr buffer.

YCbCr data often uses different gamma curves and signal ranges (e.g.
BT.609, BT.701, BT.2020, studio range, full-range), so its desirable
to be able to explicitly control the YCbCr to RGB conversion process
from userspace.

We're proposing adding a "CSC" (color-space conversion) property to
control this - primarily per-plane for framebuffer->pipeline CSC, but
perhaps one per CRTC too for devices which have an RGB pipeline and
want to output in YUV to the display:

Name: "CSC"
Type: ENUM | ATOMIC;
Enum values (representative):
"default":
Same behaviour as now. "Some kind" of YCbCr->RGB conversion
for YCbCr buffers, bypass for RGB buffers
"disable":
Explicitly disable all colorspace conversion (i.e. use an
identity matrix).
"YCbCr to RGB: BT.709":
Only valid for YCbCr formats. CSC in accordance with BT.709
using [16..235] for (8-bit) luma values, and [16..240] for
8-bit chroma values. For 10-bit formats, the range limits are
multiplied by 4.
"YCbCr to RGB: BT.709 full-swing":
Only valid for YCbCr formats. CSC in accordance with BT.709,
but using the full range of each channel.
"YCbCr to RGB: Use CTM":*
Only valid for YCbCr formats. Use the matrix applied via the
plane's CTM property
"RGB to RGB: Use CTM":*
Only valid for RGB formats. Use the matrix applied via the
plane's CTM property
"Use CTM":*
Valid for any format. Use the matrix applied via the plane's
CTM property
... any other values for BT.601, BT.2020, RGB to YCbCr etc. etc. as
they are required.

*This assumes color-management is enabled per-plane. We're currently
working on patches to add this mostly to be able to use per-plane
degamma, but it would be analogous to the CRTC color-management code
and so also be able to expose a per-plane CTM property.

Our hardware implements the color-space conversion as a 3x3 matrix, so
we can implement a helper to convert a CSC enum value to a CTM matrix
for use by any hardware which has a programmable CSC matrix. For any
other hardware, the driver simply needs to map the enum value to
whatever selector bits are available.

It's expected that the "Use CTM" value(s) are *not* the common case,
and most of the time userspace will use one of the provided "standard"
enum values. The three different flavours of "Use CTM" allow us to
support hardware whose CSC hardware can only be used on e.g. YCbCr
data.

Drivers can of course filter the enum list to expose whichever subset
the hardware can support.

Having thrashed this out a bit on IRC with Ville, I think the above
approach is flexible enough to support at least Mali-DP and i915,
without burdening userspace any more than necessary. It also provides
the "default" behaviour which is backwards compatible, and allows for
fully custom CSC matrices where that is supported.

We can obviously implement this as a Mali-DP driver private property,
but it would be good to come up with something to go into the core if
possible.

I'd be happy to hear any feedback,

Thanks,
Brian