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Date: Mon, 12 Feb 2024 10:55:32 +0100
From: Maxime Ripard <mripard@kernel.org>
To: Sebastian Wick <sebastian.wick@redhat.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>, 
	Thomas Zimmermann <tzimmermann@suse.de>, David Airlie <airlied@gmail.com>, 
	Daniel Vetter <daniel@ffwll.ch>, Emma Anholt <emma@anholt.net>, Jonathan Corbet <corbet@lwn.net>, 
	Sandy Huang <hjc@rock-chips.com>, Heiko =?utf-8?Q?St=C3=BCbner?= <heiko@sntech.de>, 
	Chen-Yu Tsai <wens@csie.org>, Jernej Skrabec <jernej.skrabec@gmail.com>, 
	Samuel Holland <samuel@sholland.org>, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, 
	dri-devel@lists.freedesktop.org, Hans Verkuil <hverkuil@xs4all.nl>, 
	linux-rockchip@lists.infradead.org, linux-sunxi@lists.linux.dev, 
	linux-arm-kernel@lists.infradead.org, linux-media@vger.kernel.org
Subject: Re: Re: Re: [PATCH v5 08/44] drm/connector: hdmi: Add Broadcast RGB
 property
Message-ID: <uplclresnokchsgutsd27ihv4422sob77reobw6ygx3c3cqnti@hjmrhut7l5r5>
References: <20231207-kms-hdmi-connector-state-v5-0-6538e19d634d@kernel.org>
 <20231207-kms-hdmi-connector-state-v5-8-6538e19d634d@kernel.org>
 <20240115143308.GA159345@toolbox>
 <niqn7eql5neyfp5ficdfisdpmlwrprovqn5g7lgcfwoe74ds23@7fr4yv2miqe7>
 <20240209203046.GA996172@toolbox>
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On Fri, Feb 09, 2024 at 09:30:46PM +0100, Sebastian Wick wrote:
> On Fri, Feb 02, 2024 at 04:49:04PM +0100, Maxime Ripard wrote:
> > Hi Sebastian,
> >=20
> > On Mon, Jan 15, 2024 at 03:33:08PM +0100, Sebastian Wick wrote:
> > > >  /**
> > > >   * DOC: HDMI connector properties
> > > >   *
> > > > + * Broadcast RGB
> > > > + *      Indicates the RGB Quantization Range (Full vs Limited) use=
d.
> > > > + *      Infoframes will be generated according to that value.
> > > > + *
> > > > + *      The value of this property can be one of the following:
> > > > + *
> > > > + *      Automatic:
> > > > + *              RGB Range is selected automatically based on the m=
ode
> > > > + *              according to the HDMI specifications.
> > > > + *
> > > > + *      Full:
> > > > + *              Full RGB Range is forced.
> > > > + *
> > > > + *      Limited 16:235:
> > > > + *              Limited RGB Range is forced. Unlike the name sugge=
sts,
> > > > + *              this works for any number of bits-per-component.
> > > > + *
> > > > + *      Drivers can set up this property by calling
> > > > + *      drm_connector_attach_broadcast_rgb_property().
> > > > + *
> > >=20
> > > This is a good time to document this in more detail. There might be t=
wo
> > > different things being affected:
> > >=20
> > > 1. The signalling (InfoFrame/SDP/...)
> > > 2. The color pipeline processing
> > >=20
> > > All values of Broadcast RGB always affect the color pipeline processi=
ng
> > > such that a full-range input to the CRTC is converted to either full-=
 or
> > > limited-range, depending on what the monitor is supposed to accept.
> > >=20
> > > When automatic is selected, does that mean that there is no signallin=
g,
> > > or that the signalling matches what the monitor is supposed to accept
> > > according to the spec? Also, is this really HDMI specific?
> > >=20
> > > When full or limited is selected and the monitor doesn't support the
> > > signalling, what happens?
> >=20
> > Leaving the YCbCr vs RGB discussion aside, would this be better ?
>=20
> Yes, it is. Thanks.

Great, it'll be in the next version.

> We do have to resolve the YCbCr vs RGB issue though.
>=20
> >  * Broadcast RGB (HDMI specific)
> >  *      Indicates the Quantization Range (Full vs Limited) used. The co=
lor
> >  *      processing pipeline will be adjusted to match the value of the
>=20
> Ah, another thing no note here is that the CRTC as configured by user
> space must always produce full range pixels.

Added too

Thanks

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