[PATCH xf86-video-amdgpu 0/5] Implementing non-legacy color management

Michel Dänzer michel at daenzer.net
Mon Apr 9 14:10:27 UTC 2018

Hi Leo,

apologies for the late follow-up; I was on vacation and then backlogged.

On 2018-03-26 10:00 PM, sunpeng.li at amd.com wrote:
> From: "Leo (Sunpeng) Li" <sunpeng.li at amd.com>
> These patches will enable modification of non-legacy color management
> properties via xrandr.
> On top of the current legacy gamma, DRM allows the setting of three color
> management tables: the degamma LUT, the color transform matrix (CTM), and the
> regamma LUT. To user land, all of them are stored as DRM blobs, and are
> referenced by CRTC properties via their blob IDs.
> Therefore, in order to allow setting color management via xrandr, we have to:
> 1. Enable modification of CRTC properties via xrandr
> 2. Allow configuring and changing DRM blob properties via their IDs
> 3. Ensure compatability with legacy gamma
> The first three patches does the above, while the last two does some
> refactoring work to remove repetative code.
> A note to reviewers, I'm a little unclear on whether this woks when one CRTC is
> connected to multiple outputs. I expect that changing a CRTC property via one
> of its outputs will update for that output only, since randr still understands
> it as an "output property". In whic case, there needs to be a v2.

Yes, I suspect so.

> However, I'm not sure how I can setup a test for this. Let me know if you have tips.

Something like

xrandr --output DVI-D-1 --off --output DVI-D-2 --off
xrandr --output DVI-D-1 --crtc 0 --mode 1920x1080 --output DVI-D-2
 --crtc 0 --mode 1920x1080

and then verify with xrandr --verbose that both outputs are actually
using the same CRTC. Note that I'm getting an error on the second step
when trying this right now, so there may be something preventing using
the same CRTC for multiple outputs. But AFAIK at least in theory it's

I will follow up with some comments on individual patches.

Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer

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