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Date:   Mon, 29 Mar 2021 14:11:15 +0000
To:     Maxime Ripard <maxime@cerno.tech>
From:   Simon Ser <contact@emersion.fr>
Cc:     Paul Cercueil <paul@crapouillou.net>,
        Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
        Thomas Zimmermann <tzimmermann@suse.de>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>, od@zcrc.me,
        dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
        stable@vger.kernel.org
Reply-To: Simon Ser <contact@emersion.fr>
Subject: Re: [PATCH] drm: DON'T require each CRTC to have a unique primary plane
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On Monday, March 29th, 2021 at 4:07 PM, Maxime Ripard <maxime@cerno.tech> w=
rote:

> Since it looks like you have two mutually exclusive planes, just expose
> one and be done with it?

You can expose the other as an overlay. Clever user-space will be able
to figure out that the more advanced plane can be used if the primary
plane is disabled.

But yeah, I don't think exposing two primary planes makes sense. The
"primary" bit is just there for legacy user-space, it's a hint that
it's the best plane to light up for fullscreen content. It has no other
significance than that, and in particular it doesn't mean that it's
incompatible with other primary planes.