[Intel-gfx] Intel Driver and 4K video output

[Chris Wilson]

On Thu, Apr 23, 2015 at 12:03:24PM +0200, Lukas Hejtmanek wrote:
> On Thu, Apr 23, 2015 at 10:22:31AM +0100, Chris Wilson wrote:
> > $ xrandr --output eDP1 --off --output DP1-8 --off --output DP1-9 --off ; \
> >   xrandr \
> > 	--output eDP1 --primary --preferred --crtc 0 \
> > 	--output DP1-8 --preferred --right-of eDP1 --crtc 1 \
> > 	--output DP1-9 --preferred --right-of DP1-8 --crtc 2
> 
> well, this one works!
> 
> Two caveats, have to switch DP1-8 and DP1-9, otherwise, I have switched sides.
> 
> However, I would like to have a clone. But this seems to be a bit tricky,
> I can say same-as, bud not as a conjunction of both DP1-8 and DP1-9. 
> 
> Is there any possibility to mirror eDP to both DP1-8 and DP1-9? Or the best
> I can get is independent screens? 

Anything is possible... Considering that the two halves are different
sizes to the eDP, you can either scale the DP or scale the panel. You
can try something like

xrandr \
	--output eDP1 --primary --preferred --crtc 0 \
	--output DP1-8 --preferred --scale 1.3333x0.6666 --position 1280x0  --crtc 1 \
	--output DP1-9 --preferred --scale 1.3333x0.6666 --position 0x0  --crtc 2

I probably have the scaling inverted. What should also work, but we may
have to beat the kernel up to fix a few bugs...

xrandr --addmode eDP1 3840x2160 \
	--output eDP1 --primary --mode 3840x2160 --crtc 0 \
	--output DP1-9 --preferred --position 0x0 -crtc 1 \
	--output DP1-8 --preferred --position 1920x0 -crtc 1 \

That way we should be able to use the panel fitter for hardware
downscaling. But there are all sorts of bandwidth caveats that I may have
violated, as well as the code being untested! However, the mouse will be
the wrong size. :|
 
> On NVIDIA, I had to setup xinerama to have a big single screen. However, with
> xinerama, xrandr is inoperational. So no luck here?

It's being worked on. The concept of logical screens is being brought to
xrandr, along with exporting enough information for display mangers to
automatically reconstruct the logical monitor from the tiles.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre