Re: [PATCH] drm: DON'T require each CRTC to have a unique primary plane

From: Maxime Ripard
Date: Mon Mar 29 2021 - 11:36:52 EST


On Mon, Mar 29, 2021 at 04:15:28PM +0100, Paul Cercueil wrote:
> Hi Maxime,
>
> Le lun. 29 mars 2021 à 16:07, Maxime Ripard <maxime@xxxxxxxxxx> a écrit :
> > On Sat, Mar 27, 2021 at 11:22:14AM +0000, Paul Cercueil wrote:
> > > The ingenic-drm driver has two mutually exclusive primary planes
> > > already; so the fact that a CRTC must have one and only one primary
> > > plane is an invalid assumption.
> >
> > I mean, no? It's been documented for a while that a CRTC should only
> > have a single primary, so I'd say that the invalid assumption was that
> > it was possible to have multiple primary planes for a CRTC.
>
> Documented where?
>
> I did read the doc of "enum drm_plane_type" in <drm/drm_plane.h>, and the
> DRM_PLANE_TYPE_PRIMARY describes my two planes, so I went with that.

At least since 4.9, this was in the documentation generated for DRM:
https://elixir.bootlin.com/linux/v4.9.263/source/drivers/gpu/drm/drm_plane.c#L43

Maxime

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