[Intel-gfx] Status of 30-bit color depth support for Intel Graphics on Linux

[Robert Schlabbach]

Hi,

referring to the recent exchange here:
http://www.spinics.net/lists/intel-gfx/msg91010.html

the response only mentions correct gamma ramp support, but it looks to me as if
there is much more missing than in existence when it comes to 30-bit color depth
support in Linux using Intel Graphics.

I, too, started with Ubuntu 15.10, on a Xeon E3-1275v5 connected via DP to a
Samsung U28D590 30-bit capable monitor, installed the latest Intel Graphics
drivers for Linux using Installer 1.4.0, and edited a copy of
/etc/X11/xorg.conf.failsafe to add a "DefaultDepth 30" line.

The result is an empty Ubuntu desktop. Further investigation showed that it is
no longer possible to activate the OpenGL plugin in compiz, without which the
Unity desktop cannot work.

Checking the OpenGL support with "glxinfo" only shows a single visual, which is
not 30-bit:

1 GLX Visuals
    visual  x   bf lv rg d st  colorbuffer  sr ax dp st accumbuffer  ms  cav
  id dep cl sp  sz l  ci b ro  r  g  b  a F gb bf th cl  r  g  b  a ns b eat
----------------------------------------------------------------------------
0x055 32 tc  0  32  0 r  y .   8  8  8  8 .  .  0 24  8  0  0  0  0  0 0 None

So it looks like there is missing OpenGL 30-bit color depth support as well.

In fact, it seems the 30-bit color depth "support" for Intel Graphics on Linux
right now is no more than UNACCELERATED framebuffer support.

Is that it, or did I miss a step to enable 30-bit color depth support fully?

If not, is there a roadmap by which Intel (or other project owners?) intend to
deliver full support for 30-bit color depth? Daniel mentioned "4.7" for the
gama ramp fix, is that Linux kernel 4.7? What about OpenGL support, would that
need an update by Intel, MESA, or both?

Best Regards,
-Robert Schlabbach