[PATCH v3 2/2] drm/sun4i: Use CRTC size instead of PRIMARY plane size as mixer frame.

[Roman Stratiienko]

чт, 2 янв. 2020 г., 12:08 Maxime Ripard <mripard at kernel.org>:
>
> Hi,
>
> On Wed, Jan 01, 2020 at 10:47:50PM +0200, roman.stratiienko at globallogic.com wrote:
> > From: Roman Stratiienko <roman.stratiienko at globallogic.com>
> >
> > According to DRM documentation the only difference between PRIMARY
> > and OVERLAY plane is that each CRTC must have PRIMARY plane and
> > OVERLAY are optional.
> >
> > Allow PRIMARY plane to have dimension different from full-screen.
> >
> > Fixes: 5bb5f5dafa1a ("drm/sun4i: Reorganize UI layer code in DE2")
> > Signed-off-by: Roman Stratiienko <roman.stratiienko at globallogic.com>
>
> So it applies to all the 4 patches you've sent, but this lacks some
> context.
>
> There's a few questions that should be answered here:
>   - Which situation is it fixing?

Setting primary plane size less than crtc breaks composition. Also
shifting top left corner also breaks it.

>   - What tool / userspace stack is it fixing?

I am using Android userspace and drm_hwcomposer HAL.

@Jernej, you've said that you observed similar issue. Could you share
what userspace have you used?

>   - What happens with your fix? Do you set the plane at coordinates
>     0,0 (meaning you'll crop the top-lef corner), do you center it? If
>     the plane is smaller than the CTRC size, what is set on the edges?

You can put primary plane to any part of the screen and make it as
small as 8x8 (according to the datasheet) . Background would be filled
with black color, that is default, but it also could be overridden by
setting corresponding registers.

>
>
> Thanks!
> Maxime