GPU issues after resume

[marcbelmont]

On Ubuntu 15.04 with XMonad/Gnome (window manager) and default kernel. If I suspend and then resume, dmesg gives me:

[  402.015105] [drm] stuck on render ring
[  402.015909] [drm] GPU HANG: ecode 8:0:0x85dffefd, in Xorg [1220], reason: Ring hung, action: reset
[  402.015912] [drm] GPU hangs can indicate a bug anywhere in the entire gfx stack, including userspace.
[  402.015913] [drm] Please file a _new_ bug report on bugs.freedesktop.org against DRI -> DRM/Intel
[  402.015913] [drm] drm/i915 developers can then reassign to the right component if it's not a kernel issue.
[  402.015914] [drm] The gpu crash dump is required to analyze gpu hangs, so please always attach it.
[  402.015915] [drm] GPU crash dump saved to /sys/class/drm/card0/error
[  402.023130] drm/i915: Resetting chip after gpu hang
[  413.993920] [drm] stuck on render ring
[  413.994721] [drm] GPU HANG: ecode 8:0:0x86dffefb, in Xorg [1220], reason: Ring hung, action: reset
[  414.001937] drm/i915: Resetting chip after gpu hang
[  420.001662] [drm] stuck on render ring
[  420.002456] [drm] GPU HANG: ecode 8:0:0x86dffffb, in Xorg [1220], reason: Ring hung, action: reset
[  420.002555] [drm:i915_set_reset_status [i915]] *ERROR* gpu hanging too fast, banning!
[  420.009679] drm/i915: Resetting chip after gpu hang

Upgrading to Kernel > 4, fixes the issue. Upgrading instruction can be found on http://ubuntuhandbook.org/index.php/2015/04/upgrade-to-linux-kernel-4-0-in-ubuntu/ . List of kernel packages http://kernel.ubuntu.com/~kernel-ppa/mainline/

That being said, support for GPU (i915) is still not perfect. dmesg is still showing a bunch of bad messages. But that does not seem to break things. Anyone has a better solution?

[115561.497650] i915 0000:00:02.0: BAR 6: [??? 0x00000000 flags 0x2] has bogus alignment
[115561.497719] i915 0000:00:02.0: BAR 6: [??? 0x00000000 flags 0x2] has bogus alignment
[115561.497826] i915 0000:00:02.0: BAR 6: [??? 0x00000000 flags 0x2] has bogus alignment
[115561.497841] i915 0000:00:02.0: BAR 6: [??? 0x00000000 flags 0x2] has bogus alignment
[115561.497856] i915 0000:00:02.0: BAR 6: [??? 0x00000000 flags 0x2] has bogus alignment

Note: I've read this issue is not affecting people using Unity. "If you have to use an older kernel, if you have an OpenGL program running while you suspend, it’ll resume fine (this is why it works on Unity and GNOME – they have OpenGL-based compositors)". Who knows..