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From: Andri Yngvason <andri@yngvason.is>
Date: Wed, 10 Jan 2024 10:11:32 +0000
Message-ID: <CAFNQBQzijyE4wR34AOLM45m+ryx128igVKO9zPJ5-M3afFQMxQ@mail.gmail.com>
Subject: Re: [PATCH 5/7] drm/uAPI: Add "preferred color format" drm property
 as setting for userspace
To: Maxime Ripard <mripard@kernel.org>
Cc: Harry Wentland <harry.wentland@amd.com>, Leo Li <sunpeng.li@amd.com>, 
	Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>, Alex Deucher <alexander.deucher@amd.com>, 
	=?UTF-8?Q?Christian_K=C3=B6nig?= <christian.koenig@amd.com>, 
	"Pan, Xinhui" <Xinhui.Pan@amd.com>, David Airlie <airlied@gmail.com>, Daniel Vetter <daniel@ffwll.ch>, 
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>, Thomas Zimmermann <tzimmermann@suse.de>, 
	Jani Nikula <jani.nikula@linux.intel.com>, 
	Joonas Lahtinen <joonas.lahtinen@linux.intel.com>, Rodrigo Vivi <rodrigo.vivi@intel.com>, 
	Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>, amd-gfx@lists.freedesktop.org, 
	dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, 
	intel-gfx@lists.freedesktop.org, Simon Ser <contact@emersion.fr>, 
	Werner Sembach <wse@tuxedocomputers.com>, Dan Carpenter <dan.carpenter@oracle.com>
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Hi,

mi=C3=B0., 10. jan. 2024 kl. 09:27 skrifa=C3=B0i Maxime Ripard <mripard@ker=
nel.org>:
> On Tue, Jan 09, 2024 at 06:11:02PM +0000, Andri Yngvason wrote:
> > From: Werner Sembach <wse@tuxedocomputers.com>
> >
> > Add a new general drm property "preferred color format" which can be us=
ed
> > by userspace to tell the graphic drivers to which color format to use.
> >
> > Possible options are:
> >     - auto (default/current behaviour)
> >     - rgb
> >     - ycbcr444
> >     - ycbcr422 (not supported by both amdgpu and i915)
> >     - ycbcr420
> >
> > In theory the auto option should choose the best available option for t=
he
> > current setup, but because of bad internal conversion some monitors loo=
k
> > better with rgb and some with ycbcr444.
>
> I looked at the patch and I couldn't find what is supposed to happen if
> you set it to something else than auto, and the driver can't match that.
> Are we supposed to fallback to the "auto" behaviour, or are we suppose
> to reject the mode entirely?
>
> The combination with the active output format property suggests the
> former, but we should document it explicitly.

It is also my understanding that it should fall back to the "auto"
behaviour. I will add this to the documentation.

Thanks,
Andri