Bug 104509 - Unable to set "Content Type" bit for HDMI and DisplayPort
Summary: Unable to set "Content Type" bit for HDMI and DisplayPort
Status: NEW
Alias: None
Product: xorg
Classification: Unclassified
Component: Driver/nouveau (show other bugs)
Version: unspecified
Hardware: All Linux (All)
: medium normal
Assignee: Nouveau Project
QA Contact: Xorg Project Team
URL:
Whiteboard:
Keywords:
Depends on:
Blocks:
 
Reported: 2018-01-05 23:07 UTC by N. W.
Modified: 2018-01-16 22:01 UTC (History)
0 users

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Description N. W. 2018-01-05 23:07:36 UTC
Hi,

apparently the Intel HD Graphics driver for Windows has a "IT Content" option that can be either enabled or disabled, see following screenshot for example:

https://www.howtogeek.com/wp-content/uploads/2016/12/img_5855c293ac26d.jpg

According to a post on the AVS Forum, enabling "IT Content" does the following:

http://www.avsforum.com/forum/26-home-theater-computers/1477460-theory-about-intel-s-hdmi-quantization-range-setting-full-0-255-a-7.html#post24629922

> HDMI specs "IT Content" flag is set On in video stream.
> 
> CEA-861:
> "In IT applications (e.g. involving bit mapped text),
> each pixel in the source’s frame buffer is most clearly
> displayed if it is directly mapped to a light-emitting pixel
> on the display device - such that adjacent pixels are
> completely independent and do not interact.
> The IT content bit indicates when picture content is
> composed according to common IT practice (i.e. without
> regard to Nyquist criterion) and is unsuitable for
> analog reconstruction or filtering. When the IT content bit
> is set to 1, downstream processors should pass
> pixel data unfiltered and without analog reconstruction."

Apparently there is no option for it on the nouveau Linux driver.

Can you please add an option to the nouveau Linux driver which allows to enable the "IT Content" bit?

Regards
Comment 1 N. W. 2018-01-05 23:10:08 UTC
PS:

Apparently the NVIDIA driver for Windows supports this as well, see following screenshot and forum thread for example:

http://abload.de/img/hdmi-content-typebtumj.png
https://forums.geforce.com/default/topic/814785/hdmi-content-type-api-/

Also found something on hdmi.org:

https://www.hdmi.org/manufacturer/hdmi_1_4/content_type.aspx

Apparently there is not just a setting for "IT Content", but for "gaming, movie, photograph, and text viewing modes".

And the receiving display can alter it's processing settings based on which type of content it receives.

It would be amazing if that would be possible on Linux as well.

Looks like other Linux users have complained about the lack of such an option as well:

https://github.com/ValveSoftware/SteamOS/issues/494
https://devtalk.nvidia.com/default/topic/952181/linux/is-hdmi-content-type-supported-in-any-way-/
Comment 2 N. W. 2018-01-12 18:32:00 UTC
Any update?
Comment 3 N. W. 2018-01-16 22:01:02 UTC
Any update on this one?


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