Re: [PATCH 1/7] drm: Fix drm_fixp2int_round() making it add 0.5

2024-03-16 Thread Melissa Wen 




On 16/03/2024 08:59, Arthur Grillo wrote:


On 12/03/24 15:27, Melissa Wen wrote:

On 03/06, Arthur Grillo wrote:

As well noted by Pekka[1], the rounding of drm_fixp2int_round is wrong.
To round a number, you need to add 0.5 to the number and floor that,
drm_fixp2int_round() is adding 0.076. Make it add 0.5.

[1]: 
https://lore.kernel.org/all/20240301135327.22efe0dd.pekka.paala...@collabora.com/


Hi Arthur,

thanks for addressing this issue.

Please, add a fix tag to the commit that you are fixing, so we can
easily backport. Might be this commit:
https://cgit.freedesktop.org/drm/drm-misc/commit/drivers/gpu/drm/vkms?id=ab87f558dcfb2562c3497e89600dec798a446665

Wouldn't be this commit instead?
https://cgit.freedesktop.org/drm/drm-misc/commit/?id=8b25320887d7feac98875546ea0f521628b745bb

Yes, you're right!

Melissa


Best Regards,
~Arthur Grillo



Suggested-by: Pekka Paalanen 
Signed-off-by: Arthur Grillo 
---
  include/drm/drm_fixed.h | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/drm/drm_fixed.h b/include/drm/drm_fixed.h
index 0c9f917a4d4b..de3a79909ac9 100644
--- a/include/drm/drm_fixed.h
+++ b/include/drm/drm_fixed.h
@@ -90,7 +90,7 @@ static inline int drm_fixp2int(s64 a)
  
  static inline int drm_fixp2int_round(s64 a)

  {
-   return drm_fixp2int(a + (1 << (DRM_FIXED_POINT_HALF - 1)));

Also, this is the only usage of DRM_FIXED_POINT_HALF. Can you also
remove it as it won't be used anymore?


+   return drm_fixp2int(a + DRM_FIXED_ONE / 2);

Would this division be equivalent to just shifting 1ULL by 31 instead of
32 as done in DRM_FIXED_ONE?

Melissa


  }
  
  static inline int drm_fixp2int_ceil(s64 a)


--
2.43.0

Re: [PATCH 1/7] drm: Fix drm_fixp2int_round() making it add 0.5

2024-03-16 Thread Arthur Grillo 



On 12/03/24 15:27, Melissa Wen wrote:
> On 03/06, Arthur Grillo wrote:
>> As well noted by Pekka[1], the rounding of drm_fixp2int_round is wrong.
>> To round a number, you need to add 0.5 to the number and floor that,
>> drm_fixp2int_round() is adding 0.076. Make it add 0.5.
>>
>> [1]: 
>> https://lore.kernel.org/all/20240301135327.22efe0dd.pekka.paala...@collabora.com/
>>
> Hi Arthur,
> 
> thanks for addressing this issue.
> 
> Please, add a fix tag to the commit that you are fixing, so we can
> easily backport. Might be this commit:
> https://cgit.freedesktop.org/drm/drm-misc/commit/drivers/gpu/drm/vkms?id=ab87f558dcfb2562c3497e89600dec798a446665

Wouldn't be this commit instead?
https://cgit.freedesktop.org/drm/drm-misc/commit/?id=8b25320887d7feac98875546ea0f521628b745bb

Best Regards,
~Arthur Grillo


>> Suggested-by: Pekka Paalanen 
>> Signed-off-by: Arthur Grillo 
>> ---
>>  include/drm/drm_fixed.h | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/include/drm/drm_fixed.h b/include/drm/drm_fixed.h
>> index 0c9f917a4d4b..de3a79909ac9 100644
>> --- a/include/drm/drm_fixed.h
>> +++ b/include/drm/drm_fixed.h
>> @@ -90,7 +90,7 @@ static inline int drm_fixp2int(s64 a)
>>  
>>  static inline int drm_fixp2int_round(s64 a)
>>  {
>> -return drm_fixp2int(a + (1 << (DRM_FIXED_POINT_HALF - 1)));
> Also, this is the only usage of DRM_FIXED_POINT_HALF. Can you also
> remove it as it won't be used anymore?
> 
>> +return drm_fixp2int(a + DRM_FIXED_ONE / 2);
> Would this division be equivalent to just shifting 1ULL by 31 instead of
> 32 as done in DRM_FIXED_ONE?
> 
> Melissa
> 
>>  }
>>  
>>  static inline int drm_fixp2int_ceil(s64 a)
>>
>> -- 
>> 2.43.0
>>

Re: [PATCH 1/7] drm: Fix drm_fixp2int_round() making it add 0.5

2024-03-14 Thread Harry Wentland 



On 2024-03-14 09:31, Melissa Wen wrote:
> On 03/14, Melissa Wen wrote:
>> On 03/13, Arthur Grillo wrote:
>>>
>>>
>>> On 12/03/24 15:27, Melissa Wen wrote:
 On 03/06, Arthur Grillo wrote:
> As well noted by Pekka[1], the rounding of drm_fixp2int_round is wrong.
> To round a number, you need to add 0.5 to the number and floor that,
> drm_fixp2int_round() is adding 0.076. Make it add 0.5.
>
> [1]: 
> https://lore.kernel.org/all/20240301135327.22efe0dd.pekka.paala...@collabora.com/
>
 Hi Arthur,

 thanks for addressing this issue.

 Please, add a fix tag to the commit that you are fixing, so we can
 easily backport. Might be this commit:
 https://cgit.freedesktop.org/drm/drm-misc/commit/drivers/gpu/drm/vkms?id=ab87f558dcfb2562c3497e89600dec798a446665
> Suggested-by: Pekka Paalanen 
> Signed-off-by: Arthur Grillo 
> ---
>  include/drm/drm_fixed.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/drm/drm_fixed.h b/include/drm/drm_fixed.h
> index 0c9f917a4d4b..de3a79909ac9 100644
> --- a/include/drm/drm_fixed.h
> +++ b/include/drm/drm_fixed.h
> @@ -90,7 +90,7 @@ static inline int drm_fixp2int(s64 a)
>  
>  static inline int drm_fixp2int_round(s64 a)
>  {
> - return drm_fixp2int(a + (1 << (DRM_FIXED_POINT_HALF - 1)));
 Also, this is the only usage of DRM_FIXED_POINT_HALF. Can you also
 remove it as it won't be used anymore?

> + return drm_fixp2int(a + DRM_FIXED_ONE / 2);
 Would this division be equivalent to just shifting 1ULL by 31 instead of
 32 as done in DRM_FIXED_ONE?
>>>
>>> Yes, but I think the division makes it easier to understand what is
>>> going on.
>>
>> Right. I was thinking about slightly better performance, but I don't
>> have any data. We can go with this since you consider more readable,
>> anyway.
> 
> Just checked that Harry proposed in another patch[1] this:
> `#define DRM_FIXED_HALF   0x8000ll` for the 0.5 const
> 
> Doesn't it sounds better?
> 

I tend to agree with Arthur and Pekka. DRM_FIXED_ONE / 2 makes it
really clear what's happening here. And I'd imagine compilers would
optimize it out anyways.

Obviously not opposed to a define but if it's only used in one place
I don't think it matters much.

Harry

> [1] 
> https://lore.kernel.org/dri-devel/20240226211100.100108-4-harry.wentl...@amd.com/
>>
>> Can you send another version addressing the other comments? Then I can
>> cherry-pick and already apply the fix.
>>
>> Thanks,
>>
>> Melissa
>>
>>>
>>> Best Regards,
>>> ~Arthur Grillo
>>>

 Melissa

>  }
>  
>  static inline int drm_fixp2int_ceil(s64 a)
>
> -- 
> 2.43.0
>

Re: [PATCH 1/7] drm: Fix drm_fixp2int_round() making it add 0.5

2024-03-14 Thread Melissa Wen 
On 03/14, Melissa Wen wrote:
> On 03/13, Arthur Grillo wrote:
> > 
> > 
> > On 12/03/24 15:27, Melissa Wen wrote:
> > > On 03/06, Arthur Grillo wrote:
> > >> As well noted by Pekka[1], the rounding of drm_fixp2int_round is wrong.
> > >> To round a number, you need to add 0.5 to the number and floor that,
> > >> drm_fixp2int_round() is adding 0.076. Make it add 0.5.
> > >>
> > >> [1]: 
> > >> https://lore.kernel.org/all/20240301135327.22efe0dd.pekka.paala...@collabora.com/
> > >>
> > > Hi Arthur,
> > > 
> > > thanks for addressing this issue.
> > > 
> > > Please, add a fix tag to the commit that you are fixing, so we can
> > > easily backport. Might be this commit:
> > > https://cgit.freedesktop.org/drm/drm-misc/commit/drivers/gpu/drm/vkms?id=ab87f558dcfb2562c3497e89600dec798a446665
> > >> Suggested-by: Pekka Paalanen 
> > >> Signed-off-by: Arthur Grillo 
> > >> ---
> > >>  include/drm/drm_fixed.h | 2 +-
> > >>  1 file changed, 1 insertion(+), 1 deletion(-)
> > >>
> > >> diff --git a/include/drm/drm_fixed.h b/include/drm/drm_fixed.h
> > >> index 0c9f917a4d4b..de3a79909ac9 100644
> > >> --- a/include/drm/drm_fixed.h
> > >> +++ b/include/drm/drm_fixed.h
> > >> @@ -90,7 +90,7 @@ static inline int drm_fixp2int(s64 a)
> > >>  
> > >>  static inline int drm_fixp2int_round(s64 a)
> > >>  {
> > >> -return drm_fixp2int(a + (1 << (DRM_FIXED_POINT_HALF - 1)));
> > > Also, this is the only usage of DRM_FIXED_POINT_HALF. Can you also
> > > remove it as it won't be used anymore?
> > > 
> > >> +return drm_fixp2int(a + DRM_FIXED_ONE / 2);
> > > Would this division be equivalent to just shifting 1ULL by 31 instead of
> > > 32 as done in DRM_FIXED_ONE?
> > 
> > Yes, but I think the division makes it easier to understand what is
> > going on.
> 
> Right. I was thinking about slightly better performance, but I don't
> have any data. We can go with this since you consider more readable,
> anyway.

Just checked that Harry proposed in another patch[1] this:
`#define DRM_FIXED_HALF 0x8000ll` for the 0.5 const

Doesn't it sounds better?

[1] 
https://lore.kernel.org/dri-devel/20240226211100.100108-4-harry.wentl...@amd.com/
> 
> Can you send another version addressing the other comments? Then I can
> cherry-pick and already apply the fix.
> 
> Thanks,
> 
> Melissa
> 
> > 
> > Best Regards,
> > ~Arthur Grillo
> > 
> > > 
> > > Melissa
> > > 
> > >>  }
> > >>  
> > >>  static inline int drm_fixp2int_ceil(s64 a)
> > >>
> > >> -- 
> > >> 2.43.0
> > >>

Re: [PATCH 1/7] drm: Fix drm_fixp2int_round() making it add 0.5

2024-03-14 Thread Pekka Paalanen 
On Thu, 14 Mar 2024 09:59:39 -0300
Melissa Wen  wrote:

> On 03/13, Arthur Grillo wrote:
> > 
> > 
> > On 12/03/24 15:27, Melissa Wen wrote:  
> > > On 03/06, Arthur Grillo wrote:  
> > >> As well noted by Pekka[1], the rounding of drm_fixp2int_round is wrong.
> > >> To round a number, you need to add 0.5 to the number and floor that,
> > >> drm_fixp2int_round() is adding 0.076. Make it add 0.5.
> > >>
> > >> [1]: 
> > >> https://lore.kernel.org/all/20240301135327.22efe0dd.pekka.paala...@collabora.com/
> > >>  
> > > Hi Arthur,
> > > 
> > > thanks for addressing this issue.
> > > 
> > > Please, add a fix tag to the commit that you are fixing, so we can
> > > easily backport. Might be this commit:
> > > https://cgit.freedesktop.org/drm/drm-misc/commit/drivers/gpu/drm/vkms?id=ab87f558dcfb2562c3497e89600dec798a446665
> > >   
> > >> Suggested-by: Pekka Paalanen 
> > >> Signed-off-by: Arthur Grillo 
> > >> ---
> > >>  include/drm/drm_fixed.h | 2 +-
> > >>  1 file changed, 1 insertion(+), 1 deletion(-)
> > >>
> > >> diff --git a/include/drm/drm_fixed.h b/include/drm/drm_fixed.h
> > >> index 0c9f917a4d4b..de3a79909ac9 100644
> > >> --- a/include/drm/drm_fixed.h
> > >> +++ b/include/drm/drm_fixed.h
> > >> @@ -90,7 +90,7 @@ static inline int drm_fixp2int(s64 a)
> > >>  
> > >>  static inline int drm_fixp2int_round(s64 a)
> > >>  {
> > >> -return drm_fixp2int(a + (1 << (DRM_FIXED_POINT_HALF - 1)));  
> > > Also, this is the only usage of DRM_FIXED_POINT_HALF. Can you also
> > > remove it as it won't be used anymore?
> > >   
> > >> +return drm_fixp2int(a + DRM_FIXED_ONE / 2);  
> > > Would this division be equivalent to just shifting 1ULL by 31 instead of
> > > 32 as done in DRM_FIXED_ONE?  
> > 
> > Yes, but I think the division makes it easier to understand what is
> > going on.  
> 
> Right. I was thinking about slightly better performance, but I don't
> have any data. We can go with this since you consider more readable,
> anyway.

Those are constants, the compiler should compute it at build time in
both styles.

I like the DRM_FIXED_ONE / 2 style, it's semantically obvious. Bit
shift is less obvious.


Thanks,
pq


pgpmgraeOkMcR.pgp
Description: OpenPGP digital signature

Re: [PATCH 1/7] drm: Fix drm_fixp2int_round() making it add 0.5

2024-03-14 Thread Melissa Wen 
On 03/13, Arthur Grillo wrote:
> 
> 
> On 12/03/24 15:27, Melissa Wen wrote:
> > On 03/06, Arthur Grillo wrote:
> >> As well noted by Pekka[1], the rounding of drm_fixp2int_round is wrong.
> >> To round a number, you need to add 0.5 to the number and floor that,
> >> drm_fixp2int_round() is adding 0.076. Make it add 0.5.
> >>
> >> [1]: 
> >> https://lore.kernel.org/all/20240301135327.22efe0dd.pekka.paala...@collabora.com/
> >>
> > Hi Arthur,
> > 
> > thanks for addressing this issue.
> > 
> > Please, add a fix tag to the commit that you are fixing, so we can
> > easily backport. Might be this commit:
> > https://cgit.freedesktop.org/drm/drm-misc/commit/drivers/gpu/drm/vkms?id=ab87f558dcfb2562c3497e89600dec798a446665
> >> Suggested-by: Pekka Paalanen 
> >> Signed-off-by: Arthur Grillo 
> >> ---
> >>  include/drm/drm_fixed.h | 2 +-
> >>  1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/include/drm/drm_fixed.h b/include/drm/drm_fixed.h
> >> index 0c9f917a4d4b..de3a79909ac9 100644
> >> --- a/include/drm/drm_fixed.h
> >> +++ b/include/drm/drm_fixed.h
> >> @@ -90,7 +90,7 @@ static inline int drm_fixp2int(s64 a)
> >>  
> >>  static inline int drm_fixp2int_round(s64 a)
> >>  {
> >> -  return drm_fixp2int(a + (1 << (DRM_FIXED_POINT_HALF - 1)));
> > Also, this is the only usage of DRM_FIXED_POINT_HALF. Can you also
> > remove it as it won't be used anymore?
> > 
> >> +  return drm_fixp2int(a + DRM_FIXED_ONE / 2);
> > Would this division be equivalent to just shifting 1ULL by 31 instead of
> > 32 as done in DRM_FIXED_ONE?
> 
> Yes, but I think the division makes it easier to understand what is
> going on.

Right. I was thinking about slightly better performance, but I don't
have any data. We can go with this since you consider more readable,
anyway.

Can you send another version addressing the other comments? Then I can
cherry-pick and already apply the fix.

Thanks,

Melissa

> 
> Best Regards,
> ~Arthur Grillo
> 
> > 
> > Melissa
> > 
> >>  }
> >>  
> >>  static inline int drm_fixp2int_ceil(s64 a)
> >>
> >> -- 
> >> 2.43.0
> >>

Re: [PATCH 1/7] drm: Fix drm_fixp2int_round() making it add 0.5

2024-03-13 Thread Arthur Grillo 



On 12/03/24 15:27, Melissa Wen wrote:
> On 03/06, Arthur Grillo wrote:
>> As well noted by Pekka[1], the rounding of drm_fixp2int_round is wrong.
>> To round a number, you need to add 0.5 to the number and floor that,
>> drm_fixp2int_round() is adding 0.076. Make it add 0.5.
>>
>> [1]: 
>> https://lore.kernel.org/all/20240301135327.22efe0dd.pekka.paala...@collabora.com/
>>
> Hi Arthur,
> 
> thanks for addressing this issue.
> 
> Please, add a fix tag to the commit that you are fixing, so we can
> easily backport. Might be this commit:
> https://cgit.freedesktop.org/drm/drm-misc/commit/drivers/gpu/drm/vkms?id=ab87f558dcfb2562c3497e89600dec798a446665
>> Suggested-by: Pekka Paalanen 
>> Signed-off-by: Arthur Grillo 
>> ---
>>  include/drm/drm_fixed.h | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/include/drm/drm_fixed.h b/include/drm/drm_fixed.h
>> index 0c9f917a4d4b..de3a79909ac9 100644
>> --- a/include/drm/drm_fixed.h
>> +++ b/include/drm/drm_fixed.h
>> @@ -90,7 +90,7 @@ static inline int drm_fixp2int(s64 a)
>>  
>>  static inline int drm_fixp2int_round(s64 a)
>>  {
>> -return drm_fixp2int(a + (1 << (DRM_FIXED_POINT_HALF - 1)));
> Also, this is the only usage of DRM_FIXED_POINT_HALF. Can you also
> remove it as it won't be used anymore?
> 
>> +return drm_fixp2int(a + DRM_FIXED_ONE / 2);
> Would this division be equivalent to just shifting 1ULL by 31 instead of
> 32 as done in DRM_FIXED_ONE?

Yes, but I think the division makes it easier to understand what is
going on.

Best Regards,
~Arthur Grillo

> 
> Melissa
> 
>>  }
>>  
>>  static inline int drm_fixp2int_ceil(s64 a)
>>
>> -- 
>> 2.43.0
>>

Re: [PATCH 1/7] drm: Fix drm_fixp2int_round() making it add 0.5

2024-03-12 Thread Melissa Wen 
On 03/06, Arthur Grillo wrote:
> As well noted by Pekka[1], the rounding of drm_fixp2int_round is wrong.
> To round a number, you need to add 0.5 to the number and floor that,
> drm_fixp2int_round() is adding 0.076. Make it add 0.5.
> 
> [1]: 
> https://lore.kernel.org/all/20240301135327.22efe0dd.pekka.paala...@collabora.com/
> 
Hi Arthur,

thanks for addressing this issue.

Please, add a fix tag to the commit that you are fixing, so we can
easily backport. Might be this commit:
https://cgit.freedesktop.org/drm/drm-misc/commit/drivers/gpu/drm/vkms?id=ab87f558dcfb2562c3497e89600dec798a446665
> Suggested-by: Pekka Paalanen 
> Signed-off-by: Arthur Grillo 
> ---
>  include/drm/drm_fixed.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/drm/drm_fixed.h b/include/drm/drm_fixed.h
> index 0c9f917a4d4b..de3a79909ac9 100644
> --- a/include/drm/drm_fixed.h
> +++ b/include/drm/drm_fixed.h
> @@ -90,7 +90,7 @@ static inline int drm_fixp2int(s64 a)
>  
>  static inline int drm_fixp2int_round(s64 a)
>  {
> - return drm_fixp2int(a + (1 << (DRM_FIXED_POINT_HALF - 1)));
Also, this is the only usage of DRM_FIXED_POINT_HALF. Can you also
remove it as it won't be used anymore?

> + return drm_fixp2int(a + DRM_FIXED_ONE / 2);
Would this division be equivalent to just shifting 1ULL by 31 instead of
32 as done in DRM_FIXED_ONE?

Melissa

>  }
>  
>  static inline int drm_fixp2int_ceil(s64 a)
> 
> -- 
> 2.43.0
>

Re: [PATCH 1/7] drm: Fix drm_fixp2int_round() making it add 0.5

2024-03-08 Thread Harry Wentland 

On 2024-03-06 15:03, Arthur Grillo wrote:

As well noted by Pekka[1], the rounding of drm_fixp2int_round is wrong.
To round a number, you need to add 0.5 to the number and floor that,
drm_fixp2int_round() is adding 0.076. Make it add 0.5.

[1]: 
https://lore.kernel.org/all/20240301135327.22efe0dd.pekka.paala...@collabora.com/

Suggested-by: Pekka Paalanen 
Signed-off-by: Arthur Grillo 


Reviewed-by: Harry Wentland 

I had a different jab at this [1], but your patch is cleaner.

https://patchwork.freedesktop.org/patch/579978/?series=123446=4

Harry


---
  include/drm/drm_fixed.h | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/drm/drm_fixed.h b/include/drm/drm_fixed.h
index 0c9f917a4d4b..de3a79909ac9 100644
--- a/include/drm/drm_fixed.h
+++ b/include/drm/drm_fixed.h
@@ -90,7 +90,7 @@ static inline int drm_fixp2int(s64 a)
  
  static inline int drm_fixp2int_round(s64 a)

  {
-   return drm_fixp2int(a + (1 << (DRM_FIXED_POINT_HALF - 1)));
+   return drm_fixp2int(a + DRM_FIXED_ONE / 2);
  }
  
  static inline int drm_fixp2int_ceil(s64 a)

[PATCH 1/7] drm: Fix drm_fixp2int_round() making it add 0.5

2024-03-06 Thread Arthur Grillo 
As well noted by Pekka[1], the rounding of drm_fixp2int_round is wrong.
To round a number, you need to add 0.5 to the number and floor that,
drm_fixp2int_round() is adding 0.076. Make it add 0.5.

[1]: 
https://lore.kernel.org/all/20240301135327.22efe0dd.pekka.paala...@collabora.com/

Suggested-by: Pekka Paalanen 
Signed-off-by: Arthur Grillo 
---
 include/drm/drm_fixed.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/drm/drm_fixed.h b/include/drm/drm_fixed.h
index 0c9f917a4d4b..de3a79909ac9 100644
--- a/include/drm/drm_fixed.h
+++ b/include/drm/drm_fixed.h
@@ -90,7 +90,7 @@ static inline int drm_fixp2int(s64 a)
 
 static inline int drm_fixp2int_round(s64 a)
 {
-   return drm_fixp2int(a + (1 << (DRM_FIXED_POINT_HALF - 1)));
+   return drm_fixp2int(a + DRM_FIXED_ONE / 2);
 }
 
 static inline int drm_fixp2int_ceil(s64 a)

-- 
2.43.0