[Bug 82829] [hsw Color] Intel Haswell GPU HD4400 has wrong color management on external screen

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=82829

--- Comment #14 from Ville Syrjala <ville.syrjala at linux.intel.com> ---
(In reply to comment #9)
> We do this with Broadcast RGB Automatic because DPv1.2 says, "When a Source
> device is transmitting a RGB stream with a video timing format called out in
> CEA-861C Section 5 as using CEA range RGB, it must use the CEA range RGB."
> 
> However it also says, "However, a Source device may transmit all code values
> from zero to the maximum even when it declares the CEA range in the Main
> Stream Attributes. It is the responsibility of the Sink device to limit the
> pixel value
> range as needed."
> 
> I wonder if we could do that. Ville?

My interpretation of the latter clause is that the source is allowed to include
"invalid" pixel values in the data and the sink must be ready to receive them
and clamp them to the limited range. So if we would send full range data and
tell the sink it's limited range the sink will just clamp it and you get the
"crushed blacks" syndrome.

I really wonder how so many display get away with ignoring the spec. I can only
assume that the compliance tests don't check for this issue, and thus you can
get the DP sticker on your product even if it doesn't do as the spec says.

-- 
You are receiving this mail because:
You are the QA Contact for the bug.
You are on the CC list for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.freedesktop.org/archives/intel-gfx-bugs/attachments/20140918/c87bd3cb/attachment-0001.html>