On Fri, Jan 12, 2018 at 04:51:16PM +0100, Maxime Ripard wrote:
Hi,
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. 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.
Do you need only the info that a particular channel has an alpha component, or do you also need the number of bits?
Currently, only the info whether alpha component is present in a particular channel. I saw your patch and thought that instead of returning true/false, it might be useful to capture the number of alpha bits for each format.
In the former case, then my serie sent earlier this week would help I guess.
Maxime
-- Maxime Ripard, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com