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From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Cc: linux-renesas-soc@vger.kernel.org,
	dri-devel@lists.freedesktop.org,
	Alexandru-Cosmin Gheorghe <Alexandru-Cosmin.Gheorghe@arm.com>,
	Gustavo Padovan <gustavo@padovan.org>,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Sean Paul <sean@poorly.run>, David Airlie <airlied@linux.ie>,
	open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/2] drm/atomic: Initialise planes with opaque alpha values
Date: Thu, 20 Sep 2018 14:17:05 +0300	[thread overview]
Message-ID: <1760492.77853pnPW8@avalon> (raw)
In-Reply-To: <20180919155700.10342-2-kieran.bingham+renesas@ideasonboard.com>

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




  parent reply	other threads:[~2018-09-20 11:16 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20180919155700.10342-1-kieran.bingham+renesas@ideasonboard.com>
2018-09-19 15:56 ` Kieran Bingham
2018-09-19 16:15   ` Ville Syrjälä
2018-09-19 16:43     ` Alexandru-Cosmin Gheorghe
2018-09-20 10:03       ` Kieran Bingham
2018-09-20 10:19         ` Alexandru-Cosmin Gheorghe
2018-09-20 11:17   ` Laurent Pinchart [this message]
2018-09-19 15:56 ` [PATCH 2/2] drm: rcar-du: Enable alpha property on primary planes Kieran Bingham
2018-09-20 11:22   ` Laurent Pinchart
2018-11-21 18:29     ` Laurent Pinchart
2018-11-21 21:10       ` Kieran Bingham

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