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

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Date:   Thu, 20 Sep 2018 11:03:12 +0100
From:   Kieran Bingham <kieran.bingham+renesas@...asonboard.com>
To:     Alexandru-Cosmin Gheorghe <Alexandru-Cosmin.Gheorghe@....com>,
        Ville Syrjälä <ville.syrjala@...ux.intel.com>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc:     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 Alexandru,

On 19/09/18 17:43, Alexandru-Cosmin Gheorghe wrote:
> 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.

I've submitted a separate patch for the rcar-du which enables the alpha
property for the primary plane - and it incorporates a "Fixes:
161ad653d6c9 ("drm: rcar-du: Use __drm_atomic_helper_plane_reset
instead of copying the logic")" tag.

Technically that should be sufficient to get that fix into v4.19 I
believe ...

But if you feel that this patch should also be included - we could add
the same tag to this patch, and get it queued up for v4.19 fixes?

--
Regards

Kieran

> 
>>
>>>  	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
> 

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