[Intel-gfx] [PATCH] Remove illogical/bogus "Automatic" mode from "Broadcast RGB" property

[Damien Lespiau]

On Wed, Apr 08, 2015 at 07:18:06PM +0800, Tom Yan wrote:
> https://bugzilla.kernel.org/show_bug.cgi?id=94921
> 
> As mentioned in the above bug report, switching output color range
> "Automatically" according to current mode does not make sense in
> computer use case.

Current code seems correct to me after re-reading CEA-861-E again. However can
we do better? Maybe! From the spec:

"The QS (AVI Q support) bit of byte 3 allows a display to declare that it
supports the reception of either type of quantization range for any video
format, under the direction of InfoFrame Q data (see Section 6.4 for
information concerning bits Q1 and Q0). This allows a source to override the
default quantization range for any video format.  If the sink declares a
selectable RGB Quantization Range (QS=1) then it shall expect limited range
pixel values if it receives Q=1 and it shall expect full range pixel values if
it receives Q=2 (see section 6.4). For other values of Q, the sink shall expect
pixel values with the default range for the transmitted video format."

So, for sinks that support it, we could default to sending the full
range picture and overriding the quantization bit in the AVI infoframe.

You could you try to run edid-decode [1] on your sink EDID to check if
it supports overriding the quantization level (I added decoding the VCDB
a while back).

Ville, what do you think?

--
Damien

[1] http://cgit.freedesktop.org/xorg/app/edid-decode