Re: [PATCH v12 1/2] rcar-csi2: add Renesas R-Car MIPI CSI-2 receiver documentation

[Niklas Söderlund]

Hi again,

On 2018-01-26 01:23:58 +0100, Niklas Söderlund wrote:

[snip]

> > 
> > Furthermore, as explained in a comment I made when reviewing the VIN patch 
> > series, I wonder whether we shouldn't identify the CSI-2 receiver instances 
> > by 
> > ID the same way we do with the VIN instances (using the renesas,id 
> > property). 
> > In that case I think the endpoint numbering won't matter.
> 
> The endpoint numbering here plays no part in identify the CSI-2 receiver 
> instances nor dose it carry any other information. I still think it's 
> neat to define the binding like this as it more explicit and IMHO this 
> makes it easier to understand.

I now see that the commit message implies that they do matter but this 
is wrong. It was true before the 'renesas,id' was added to the VIN 
bindings, but as having cross dependences on bindings are bad this is no 
longer the case. I will remove that paragraph for the next version.

Sorry for the noise.

-- 
Regards,
Niklas Söderlund

Re: [PATCH v12 1/2] rcar-csi2: add Renesas R-Car MIPI CSI-2 receiver documentation

[Niklas Söderlund]

Hi Laurent,

Thanks for your comments.

On 2017-12-11 20:00:21 +0200, Laurent Pinchart wrote:
> Hi Niklas,
> 
> Thank you for the patch.
> 
> On Wednesday, 29 November 2017 21:32:34 EET Niklas Söderlund wrote:
> > Documentation for Renesas R-Car MIPI CSI-2 receiver. The CSI-2 receivers
> > are located between the video sources (CSI-2 transmitters) and the video
> > grabbers (VIN) on Gen3 of Renesas R-Car SoC.
> > 
> > Each CSI-2 device is connected to more then one VIN device which
> 
> s/then/than/
> 
> > simultaneously can receive video from the same CSI-2 device. Each VIN
> > device can also be connected to more then one CSI-2 device. The routing
> 
> s/then/than/
> 
> > of which link are used are controlled by the VIN devices. There are only
> 
> s/link are/links are/ or s/link are/link is/
> s/are controlled/is controlled/
> 
> > a few possible routes which are set by hardware limitations, which are
> > different for each SoC in the Gen3 family.
> > 
> > To work with the limitations of routing possibilities it is necessary
> > for the DT bindings to describe which VIN device is connected to which
> > CSI-2 device. This is why port 1 needs to to assign reg numbers for each
> > VIN device that be connected to it. To setup and to know which links are
> 
> s/that be/that is/

I agree with all spelling fixes above, will fix for next version, 
thanks.

> 
> > valid for each SoC is the responsibility of the VIN driver since the
> > register to configure it belongs to the VIN hardware.
> > 
> > Signed-off-by: Niklas Söderlund 
> > Acked-by: Rob Herring 
> > ---
> >  .../bindings/media/renesas,rcar-csi2.txt   | 105 ++
> >  MAINTAINERS|   1 +
> >  2 files changed, 106 insertions(+)
> >  create mode 100644
> > Documentation/devicetree/bindings/media/renesas,rcar-csi2.txt
> > 
> > diff --git a/Documentation/devicetree/bindings/media/renesas,rcar-csi2.txt
> > b/Documentation/devicetree/bindings/media/renesas,rcar-csi2.txt new file
> > mode 100644
> > index ..688afd83bf66f8cf
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/media/renesas,rcar-csi2.txt
> > @@ -0,0 +1,105 @@
> > +Renesas R-Car MIPI CSI-2
> > +
> > +
> > +The rcar-csi2 device provides MIPI CSI-2 capabilities for the Renesas R-Car
> 
> rcar-csi2 is the name of the driver, I would call it the "R-Car CSI-2 
> receiver 
> device" (or s/device/IP core/).

Yes "R-Car CSI-2 receiver device" sounds better.

> 
> > +family of devices. It is to be used in conjunction with the R-Car VIN
> > module,
> 
> The IP core itself doesn't have to be used with the VIN, but in R-Car SoCs it 
> is, so I would phrase it as "It is used ...".

Agreed.


> 
> > +which provides the video capture capabilities.
> > +
> > +Mandatory properties
> > +
> > + - compatible: Must be one or more of the following
> > +   - "renesas,r8a7795-csi2" for the R8A7795 device.
> > +   - "renesas,r8a7796-csi2" for the R8A7796 device.
> > +
> > + - reg: the register base and size for the device registers
> > + - interrupts: the interrupt for the device
> > + - clocks: Reference to the parent clock
> 
> Either capitalize the first word after the colon or don't, but please don't 
> mix them :-)

It's this not the new thing after camel case, mixed camel case notation?  
Yes looks terrible will fix for next version.

> 
> > +
> > +The device node shall contain two 'port' child nodes according to the
> > +bindings defined in Documentation/devicetree/bindings/media/
> > +video-interfaces.txt. Port 0 shall connect the node that is the video
> > +source for to the CSI-2.
> 
> Or simply "Port 0 shall connect to the CSI-2 source." ?
> 
> > Port 1 shall connect all the R-Car VIN
> > +modules, which can make use of the CSI-2 module.
> 
> And to be a bit more explicit, how about "Port 1 shall connect to all the R-
> Car VIN modules that have a hardware connection to the CSI-2 receiver." ?

The descriptions you provide are better, will use them in the next 
version. Thanks!

> 
> > +
> > +- Port 0 - Video source (Mandatory)
> 
> Nitpicking, I don't think you need to capitalize Mandatory.

:-)

> 
> > +   - Endpoint 0 - sub-node describing the endpoint that is the video source
> > +
> > +- Port 1 - VIN instances (Mandatory for all VIN present in the SoC)
> > +   - Endpoint 0 - sub-node describing the endpoint that is VIN0
> > +   - Endpoint 1 - sub-node describing the endpoint that is VIN1
> > +   - Endpoint 2 - sub-node describing the endpoint that is VIN2
> > +   - Endpoint 3 - sub-node describing the endpoint that is VIN3
> > +   - Endpoint 4 - sub-node describing the endpoint that is VIN4
> > +   - Endpoint 5 - sub-node describing the endpoint that is VIN5
> > +   - Endpoint 6 - sub-node describing the endpoint that is VIN6
> > +   - Endpoint 7 - sub-node describing the endpoint that is VIN7
> 
> Should we clarify that 

Re: [PATCH v12 1/2] rcar-csi2: add Renesas R-Car MIPI CSI-2 receiver documentation

[Laurent Pinchart]

Hi Niklas,

Thank you for the patch.

On Wednesday, 29 November 2017 21:32:34 EET Niklas Söderlund wrote:
> Documentation for Renesas R-Car MIPI CSI-2 receiver. The CSI-2 receivers
> are located between the video sources (CSI-2 transmitters) and the video
> grabbers (VIN) on Gen3 of Renesas R-Car SoC.
> 
> Each CSI-2 device is connected to more then one VIN device which

s/then/than/

> simultaneously can receive video from the same CSI-2 device. Each VIN
> device can also be connected to more then one CSI-2 device. The routing

s/then/than/

> of which link are used are controlled by the VIN devices. There are only

s/link are/links are/ or s/link are/link is/
s/are controlled/is controlled/

> a few possible routes which are set by hardware limitations, which are
> different for each SoC in the Gen3 family.
> 
> To work with the limitations of routing possibilities it is necessary
> for the DT bindings to describe which VIN device is connected to which
> CSI-2 device. This is why port 1 needs to to assign reg numbers for each
> VIN device that be connected to it. To setup and to know which links are

s/that be/that is/

> valid for each SoC is the responsibility of the VIN driver since the
> register to configure it belongs to the VIN hardware.
> 
> Signed-off-by: Niklas Söderlund 
> Acked-by: Rob Herring 
> ---
>  .../bindings/media/renesas,rcar-csi2.txt   | 105 ++
>  MAINTAINERS|   1 +
>  2 files changed, 106 insertions(+)
>  create mode 100644
> Documentation/devicetree/bindings/media/renesas,rcar-csi2.txt
> 
> diff --git a/Documentation/devicetree/bindings/media/renesas,rcar-csi2.txt
> b/Documentation/devicetree/bindings/media/renesas,rcar-csi2.txt new file
> mode 100644
> index ..688afd83bf66f8cf
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/media/renesas,rcar-csi2.txt
> @@ -0,0 +1,105 @@
> +Renesas R-Car MIPI CSI-2
> +
> +
> +The rcar-csi2 device provides MIPI CSI-2 capabilities for the Renesas R-Car

rcar-csi2 is the name of the driver, I would call it the "R-Car CSI-2 receiver 
device" (or s/device/IP core/).

> +family of devices. It is to be used in conjunction with the R-Car VIN
> module,

The IP core itself doesn't have to be used with the VIN, but in R-Car SoCs it 
is, so I would phrase it as "It is used ...".

> +which provides the video capture capabilities.
> +
> +Mandatory properties
> +
> + - compatible: Must be one or more of the following
> +   - "renesas,r8a7795-csi2" for the R8A7795 device.
> +   - "renesas,r8a7796-csi2" for the R8A7796 device.
> +
> + - reg: the register base and size for the device registers
> + - interrupts: the interrupt for the device
> + - clocks: Reference to the parent clock

Either capitalize the first word after the colon or don't, but please don't 
mix them :-)

> +
> +The device node shall contain two 'port' child nodes according to the
> +bindings defined in Documentation/devicetree/bindings/media/
> +video-interfaces.txt. Port 0 shall connect the node that is the video
> +source for to the CSI-2.

Or simply "Port 0 shall connect to the CSI-2 source." ?

> Port 1 shall connect all the R-Car VIN
> +modules, which can make use of the CSI-2 module.

And to be a bit more explicit, how about "Port 1 shall connect to all the R-
Car VIN modules that have a hardware connection to the CSI-2 receiver." ?

> +
> +- Port 0 - Video source (Mandatory)

Nitpicking, I don't think you need to capitalize Mandatory.

> + - Endpoint 0 - sub-node describing the endpoint that is the video source
> +
> +- Port 1 - VIN instances (Mandatory for all VIN present in the SoC)
> + - Endpoint 0 - sub-node describing the endpoint that is VIN0
> + - Endpoint 1 - sub-node describing the endpoint that is VIN1
> + - Endpoint 2 - sub-node describing the endpoint that is VIN2
> + - Endpoint 3 - sub-node describing the endpoint that is VIN3
> + - Endpoint 4 - sub-node describing the endpoint that is VIN4
> + - Endpoint 5 - sub-node describing the endpoint that is VIN5
> + - Endpoint 6 - sub-node describing the endpoint that is VIN6
> + - Endpoint 7 - sub-node describing the endpoint that is VIN7

Should we clarify that only a subset of those endpoints shall be present when 
the CSI-2 receiver isn't connected to all VIN instances ?

Furthermore, as explained in a comment I made when reviewing the VIN patch 
series, I wonder whether we shouldn't identify the CSI-2 receiver instances by 
ID the same way we do with the VIN instances (using the renesas,id property). 
In that case I think the endpoint numbering won't matter.

> +Example:
> +
> + csi20: csi2@fea8 {
> + compatible = "renesas,r8a7796-csi2";
> + reg = <0 0xfea8 0 0x1>;
> + interrupts = <0 184 IRQ_TYPE_LEVEL_HIGH>;
> + clocks = < CPG_MOD 714>;
> +  

Re: [PATCH v12 1/2] rcar-csi2: add Renesas R-Car MIPI CSI-2 receiver documentation

[Sakari Ailus]

On Wed, Nov 29, 2017 at 08:32:34PM +0100, Niklas Söderlund wrote:
> Documentation for Renesas R-Car MIPI CSI-2 receiver. The CSI-2 receivers
> are located between the video sources (CSI-2 transmitters) and the video
> grabbers (VIN) on Gen3 of Renesas R-Car SoC.
> 
> Each CSI-2 device is connected to more then one VIN device which
> simultaneously can receive video from the same CSI-2 device. Each VIN
> device can also be connected to more then one CSI-2 device. The routing
> of which link are used are controlled by the VIN devices. There are only
> a few possible routes which are set by hardware limitations, which are
> different for each SoC in the Gen3 family.
> 
> To work with the limitations of routing possibilities it is necessary
> for the DT bindings to describe which VIN device is connected to which
> CSI-2 device. This is why port 1 needs to to assign reg numbers for each
> VIN device that be connected to it. To setup and to know which links are
> valid for each SoC is the responsibility of the VIN driver since the
> register to configure it belongs to the VIN hardware.
> 
> Signed-off-by: Niklas Söderlund 
> Acked-by: Rob Herring 

Acked-by: Sakari Ailus 

-- 
Sakari Ailus
e-mail: sakari.ai...@iki.fi