On Fri, Jan 12, 2018 at 05:53:33PM +0200, Ville Syrj?l? wrote:
On Fri, Jan 12, 2018 at 03:43:49PM +0000, Ayan Halder wrote:
On Fri, Jan 12, 2018 at 04:28:34PM +0200, Ville Syrj?l? wrote:
On Fri, Jan 12, 2018 at 02:21:16PM +0000, Ayan Halder wrote:
drm_format_info does not describe the number of bits used for the alpha channel. That information is useful in a central place like drm_fourcc.c where it can be queried by the drivers that want to determine if 'alpha blending' is to be enabled or not.
Signed-off-by: Ayan Kumar Halder ayan.halder@arm.com Reviewed-by: Liviu Dudau liviu.dudau@arm.com
drivers/gpu/drm/drm_fourcc.c | 154 ++++++++++++++++++++++++------------------- include/drm/drm_fourcc.h | 3 + 2 files changed, 89 insertions(+), 68 deletions(-)
diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c index 9c0152d..073001b 100644 --- a/drivers/gpu/drm/drm_fourcc.c +++ b/drivers/gpu/drm/drm_fourcc.c
<snip> > @@ -348,3 +348,21 @@ int drm_format_plane_height(int height, uint32_t format, int plane) > return height / info->vsub; > } > EXPORT_SYMBOL(drm_format_plane_height); > + > +/** > + * drm_format_alpha_bits - get the number of bits per pixel > + * representing alpha for format > + * @format: pixel format (DRM_FORMAT_*) > + * > + * Returns: > + * The number of bits per pixel representing alpha used by the > + * specified pixel format. > + */ > +int drm_format_alpha_bits(uint32_t format) > +{ > + const struct drm_format_info *info; > + > + info = drm_format_info(format); > + return info ? info->alpha : 0; > +} > +EXPORT_SYMBOL(drm_format_alpha_bits);
Do you have an actual use for this function somewhere?
Currently, we do not have a usage for this function.
No point in adding the function then IMO.
We have helper functions for the other fields so I followed the same and added the helper function for the new field ('alpha') too.
We need 'alpha' field for each entry in 'drm_format_info' so as to determine whether to enable/disable alpha blending in Mali display processor for the particular color format.
I think that's OK. Not sure if it really helps much though since you generally have to configure other things based on the format as well, so I would expect almost everyone will end up with some kind of swicth/table to configure the hardware based on the format. Based on a quick look this doesn't really help i915 at least.
My understanding was based on the fact that alpha blending could be a common feature for all the drivers (I might be wrong). So, if we keep the number of 'alpha' bits in 'drm_format_info', it would be useful to fetch this info similar to the existing fields.
diff --git a/include/drm/drm_fourcc.h b/include/drm/drm_fourcc.h index 6942e84..5513510 100644 --- a/include/drm/drm_fourcc.h +++ b/include/drm/drm_fourcc.h @@ -38,6 +38,7 @@ struct drm_mode_fb_cmd2;
- @cpp: Number of bytes per pixel (per plane)
- @hsub: Horizontal chroma subsampling factor
- @vsub: Vertical chroma subsampling factor
*/
- @alpha: Number of bits per pixel representing alpha
struct drm_format_info { u32 format; @@ -46,6 +47,7 @@ struct drm_format_info { u8 cpp[3]; u8 hsub; u8 vsub;
- u8 alpha;
};
/** @@ -57,6 +59,7 @@ struct drm_format_name_buf { };
const struct drm_format_info *__drm_format_info(u32 format); +int drm_format_alpha_bits(u32 format); const struct drm_format_info *drm_format_info(u32 format); const struct drm_format_info * drm_get_format_info(struct drm_device *dev, -- 2.7.4
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