Re: [PATCH v2 12/43] drm/fourcc: Add format helpers for checking YUV sub-sampling

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Fri, Nov 23, 2018 at 04:55:33PM +0000, Ayan Halder wrote:
> On Fri, Nov 23, 2018 at 10:24:44AM +0100, Paul Kocialkowski wrote:
> 
> Hi Paul,
> 
> > This introduces new format helpers that use the previously-introduced
> > format info helpers for checking YUV sub-sampling.
> > 
> > Only the format fourcc is required by these helpers and the formats are
> > iterated from the list.
> > 
> > Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
> > ---
> >  drivers/gpu/drm/drm_fourcc.c | 105 +++++++++++++++++++++++++++++++++++
> >  include/drm/drm_fourcc.h     |   5 ++
> >  2 files changed, 110 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c
> > index b56e773f9f63..6d395c586ad5 100644
> > --- a/drivers/gpu/drm/drm_fourcc.c
> > +++ b/drivers/gpu/drm/drm_fourcc.c
> > @@ -492,6 +492,111 @@ bool drm_format_is_yuv_planar(uint32_t format)
> >  }
> >  EXPORT_SYMBOL(drm_format_is_yuv_planar);
> >  
> > +/**
> > + * drm_format_is_yuv_sampling_410 - check that the format is a YUV format with
> > + * 4:1:0 sub-sampling
> > + * @format: pixel format
> > + *
> > + * Returns:
> > + * A boolean indicating whether the format is a YUV format with 4:1:0
> > + * sub-sampling.
> > + */
> > +bool drm_format_is_yuv_sampling_410(uint32_t format)
> > +{
> > +	const struct drm_format_info *info;
> > +
> > +	info = drm_format_info(format);
> > +	if (!info)
> > +		return false;

Looks like you're doing a lot of drm_format_info(fb->format->format),
which doesn't make sense. Not to mention that each lookup is a linear
search so the costs may start to add up.

Unless there's a really good reason I'd rather we try to remove all
the current helpers that do these lookups, and not add any more.

> > +
> > +	return drm_format_info_is_yuv_sampling_410(info);
> > +}
> > +EXPORT_SYMBOL(drm_format_is_yuv_sampling_410);
> > +
> > +/**
> > + * drm_format_is_yuv_sampling_411 - check that the format is a YUV format with
> > + * 4:1:1 sub-sampling
> > + * @format: pixel format
> > + *
> > + * Returns:
> > + * A boolean indicating whether the format is a YUV format with 4:1:1
> > + * sub-sampling.
> > + */
> > +bool drm_format_is_yuv_sampling_411(uint32_t format)
> > +{
> > +	const struct drm_format_info *info;
> > +
> > +	info = drm_format_info(format);
> > +	if (!info)
> > +		return false;
> > +
> > +	return drm_format_info_is_yuv_sampling_411(info);
> > +}
> > +EXPORT_SYMBOL(drm_format_is_yuv_sampling_411);
> > +
> > +/**
> > + * drm_format_is_yuv_sampling_420 - check that the format is a YUV format with
> > + * 4:2:0 sub-sampling
> > + * @format: pixel format
> > + *
> > + * Returns:
> > + * A boolean indicating whether the format is a YUV format with 4:2:0
> > + * sub-sampling.
> > + */
> > +bool drm_format_is_yuv_sampling_420(uint32_t format)
> > +{
> > +	const struct drm_format_info *info;
> > +
> > +	info = drm_format_info(format);
> > +	if (!info)
> > +		return false;
> > +
> > +	return drm_format_info_is_yuv_sampling_420(info);
> > +}
> > +EXPORT_SYMBOL(drm_format_is_yuv_sampling_420);
> > +
> > +/**
> > + * drm_format_is_yuv_sampling_422 - check that the format is a YUV format with
> > + * 4:2:2 sub-sampling
> > + * @format: pixel format
> > + *
> > + * Returns:
> > + * A boolean indicating whether the format is a YUV format with 4:2:2
> > + * sub-sampling.
> > + */
> > +bool drm_format_is_yuv_sampling_422(uint32_t format)
> > +{
> > +	const struct drm_format_info *info;
> > +
> > +	info = drm_format_info(format);
> > +	if (!info)
> > +		return false;
> > +
> > +	return drm_format_info_is_yuv_sampling_422(info);
> > +}
> > +EXPORT_SYMBOL(drm_format_is_yuv_sampling_422);
> > +
> > +/**
> > + * drm_format_is_yuv_sampling_444 - check that the format is a YUV format with
> > + * 4:4:4 sub-sampling
> > + * @format: pixel format
> > + *
> > + * Returns:
> > + * A boolean indicating whether the format is a YUV format with 4:4:4
> > + * sub-sampling.
> > + */
> > +bool drm_format_is_yuv_sampling_444(uint32_t format)
> > +{
> > +	const struct drm_format_info *info;
> > +
> > +	info = drm_format_info(format);
> > +	if (!info)
> > +		return false;
> > +
> > +	return drm_format_info_is_yuv_sampling_444(info);
> > +}
> > +EXPORT_SYMBOL(drm_format_is_yuv_sampling_444);
> > +
> >  /**
> >   * drm_format_info_block_width - width in pixels of block.
> >   * @info: pixel format info
> > diff --git a/include/drm/drm_fourcc.h b/include/drm/drm_fourcc.h
> > index d170b7b323f7..cf082d8b6ad4 100644
> > --- a/include/drm/drm_fourcc.h
> > +++ b/include/drm/drm_fourcc.h
> > @@ -278,6 +278,11 @@ bool drm_format_is_yuv(uint32_t format);
> >  bool drm_format_is_yuv_packed(uint32_t format);
> >  bool drm_format_is_yuv_semiplanar(uint32_t format);
> >  bool drm_format_is_yuv_planar(uint32_t format);
> > +bool drm_format_is_yuv_sampling_410(uint32_t format);
> > +bool drm_format_is_yuv_sampling_411(uint32_t format);
> > +bool drm_format_is_yuv_sampling_420(uint32_t format);
> > +bool drm_format_is_yuv_sampling_422(uint32_t format);
> > +bool drm_format_is_yuv_sampling_444(uint32_t format);
> >  unsigned int drm_format_info_block_width(const struct drm_format_info *info,
> >  					 int plane);
> >  unsigned int drm_format_info_block_height(const struct drm_format_info *info,
> > -- 
> > 2.19.1
> > 
> From patches [PATCH v2 08/43] till [PATCH v2 12/43], looks good to me.
> 
> How about clubbing all the drm_format_helper functions together in a
> separate file (call it drm_fourcc_helper.c)? This way, we could
> keep the __drm_format_info[] only drm_fourcc.c.
> 
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-- 
Ville Syrjälä
Intel