[19:41] <chewey> I have a 4096x2160 display connected to a Skylake-driven Displayport – but I can only set a meximum resolution of 3840x2160 in Ubuntu Mate 16.04, even using the 4.6 drm-intel-next kernel. Any idea about where I could kick it?
[19:41] <chewey> Also: 60Hz would be nice :)
[20:36] <JanC> chewey: that's a Skylake limitation, I think?
[20:37] <JanC> although apparently it should *just* be possible
[20:44] <JanC> chewey: what Skylake do you have?  some have 3840x2160@60Hz as max. resolution
[20:46] <chewey> JanC: i7-6700 – and no, it's not the hardware, the Ubuntu installer from USB came up with the right resolution. I couldn't login after installation though, due to no login screen ;-)
[20:46] <JanC> oh, that one should be able to do it indeed
[20:47] <JanC> it's (mostly?) mobile processors that are limited, I think
[20:48] <JanC> and if the installer / live CD got it right, then that's really strange
[20:49] <chewey> I never quite understood the Linux graphics stack, too many layers… – I don't really know where to start.
[20:49] <JanC> chewey: did you try changing the resolution with xrandr ?
[20:49] <chewey> Jup. Bad idea: Blank screen with the monitor complaining about "signal out of range".
[20:51] <chewey> If I had never seen it working, I would suspect cables/interfaces/whatever – but I've seen it, so it is the software somehow.
[20:53] <JanC> signal out of range usually means combination of resolution and screen refresh rate are too high
[20:54] <JanC> or maybe combined with bits/pixel
[20:55] <JanC> should be 24bpp probably
[20:55] <chewey> Something like that, yes. I see the same message if I set 60Hz on the working 3840x2160.
[20:55] <chewey> So I'm running 3840x2160@30Hz at the moment. Meh.
[21:00] <JanC> I think DisplayPort also supports 30bpp (10 bits instead of 8 bits for each of R, G & B), which would require extra bandwidth of course
[21:00] <JanC> and I'm not sure if audio also counts
[21:03] <JanC> or the DRM crap
[21:09] <JanC> chewey: maybe comparing output of "xrandr --query --verbose" on the live CD vs. on the installed system shows something?
[21:10] <chewey> Good idea! – I'll try that on the next reboot.