linux-kernel - Re: [PATCH 1/2] drm/atomic: Initialise planes with opaque alpha values

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Message-ID: <20180919164347.GA21403@e114479-lin.cambridge.arm.com>
Date:   Wed, 19 Sep 2018 17:43:47 +0100
From:   Alexandru-Cosmin Gheorghe <Alexandru-Cosmin.Gheorghe@....com>
To:     Ville Syrjälä <ville.syrjala@...ux.intel.com>
Cc:     Kieran Bingham <kieran.bingham+renesas@...asonboard.com>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        linux-renesas-soc@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        David Airlie <airlied@...ux.ie>,
        open list <linux-kernel@...r.kernel.org>,
        Sean Paul <sean@...rly.run>, nd@....com
Subject: Re: [PATCH 1/2] drm/atomic: Initialise planes with opaque alpha
 values

Hi Kieran,

On Wed, Sep 19, 2018 at 07:15:45PM +0300, Ville Syrjälä wrote:
> On Wed, Sep 19, 2018 at 04:56:58PM +0100, 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@...asonboard.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;
> 
> I can't come up with a solid excuse for not initializing it always.
> 
> Reviewed-by: Ville Syrjälä <ville.syrjala@...ux.intel.com>

Neither do I, so:
Reviewed-by: Alexandru Gheorghe <alexandru-cosmin.gheorghe@....com>

And thanks again.

I plan to push it tomorrow to drm-misc-next.

Now, I've seen the plane_reset patches in the pull request for drm-next
4.20, I wonder if someone could tell me what should I do to get this
patch on that train.

> 
> >  	state->pixel_blend_mode = DRM_MODE_BLEND_PREMULTI;
> >  
> >  	plane->state = state;
> > -- 
> > 2.17.1
> > 
> > _______________________________________________
> > dri-devel mailing list
> > dri-devel@...ts.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/dri-devel
> 
> -- 
> Ville Syrjälä
> Intel

-- 
Cheers,
Alex G

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