[Intel-gfx] [REGRESSION] drm/i915: Wait for all engines to be idle as part of i915_gem_wait_for_idle()

[Nicolai Stange]

Hi,

my system (always) locks up when booting a next-20170515 kernel.

No oops. Sending magic sysrqs over serial doesn't cause any reaction.

Last few console messages before death are:

  [    7.089221] Console: switching to colour frame buffer device 128x48
  [    7.101470] radeon 0000:01:00.0: fb0: radeondrmfb frame buffer device
  [    7.111292] [drm] Initialized radeon 2.50.0 20080528 for 0000:01:00.0 on minor 1
  [    7.113056] [drm] Initialized i915 1.6.0 20170403 for 0000:00:02.0 on minor 0
  [    7.113446] [Firmware Bug]: ACPI(PEGP) defines _DOD but not _DOS
  [    7.114227] ACPI: Video Device [PEGP] (multi-head: yes  rom: no  post: no)
  [    7.114798] input: Video Bus as /devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/device:4f/LNXVIDEO:00/input/input12
  [    7.116253] ACPI: Video Device [GFX0] (multi-head: yes  rom: no  post: no)
  [    7.130432] input: Video Bus as /devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/LNXVIDEO:01/input/input13
  [    7.130481] [drm] Initialized i915 1.6.0 20170403 for 0000:00:02.0 on minor 0


Bisection lead to commit 25112b64b3d2 ("drm/i915: Wait for all engines
to be idle as part of i915_gem_wait_for_idle()"). Reverting this commit
on top of next-20170515 fixes the issue for me.

According to lspci, my i915 is a

  00:02.0 VGA compatible controller: Intel Corporation 4th Gen Core Processor Integrated Graphics Controller (rev 06) (prog-if 00 [VGA controller])

or in raw form:

  00:02.0 0300: 8086:0416 (rev 06)


Thanks,

Nicolai