lkml.org 
[lkml]   [2018]   [Sep]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [PATCH 1/2] drm/atomic: Initialise planes with opaque alpha values
Date
Hi Kieran,

Thank you for the patch.

On Wednesday, 19 September 2018 18:56:58 EEST Kieran Bingham wrote:
> Planes without an alpha property, using __drm_atomic_helper_plane_reset
> will have their plane state alpha initialised as zero, which represents
> a transparent alpha.
>
> If this value is then used for the plane, it may not be visible by
> default, and thus doesn't represent a good initialisation state.
>
> Update the default state->alpha value to DRM_BLEND_ALPHA_OPAQUE
> unconditionally when the plane is reset.
>
> Signed-off-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>

I believe the decision to use plane->alpha_property->values[1] instead of
hardcoding DRM_BLEND_ALPHA_OPAQUE comes from earlier versions of the alpha
patch series that supported driver-specific ranges for the alpha value. The
current implementation uses DRM_BLEND_ALPHA_OPAQUE unconditionally, and no
driver modifies the maximum value behind the scene, so

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

> ---
> drivers/gpu/drm/drm_atomic_helper.c | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_atomic_helper.c
> b/drivers/gpu/drm/drm_atomic_helper.c index 3cf1aa132778..e49b22381048
> 100644
> --- a/drivers/gpu/drm/drm_atomic_helper.c
> +++ b/drivers/gpu/drm/drm_atomic_helper.c
> @@ -3569,9 +3569,7 @@ void __drm_atomic_helper_plane_reset(struct drm_plane
> *plane, state->plane = plane;
> state->rotation = DRM_MODE_ROTATE_0;
>
> - /* Reset the alpha value to fully opaque if it matters */
> - if (plane->alpha_property)
> - state->alpha = plane->alpha_property->values[1];
> + state->alpha = DRM_BLEND_ALPHA_OPAQUE;
> state->pixel_blend_mode = DRM_MODE_BLEND_PREMULTI;
>
> plane->state = state;


--
Regards,

Laurent Pinchart



\
 
 \ /
  Last update: 2018-09-20 13:17    [W:0.608 / U:0.076 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site