Created attachment 95310 [details] dmesg for media forcewake lockup I get the lockup in the attached dmesg by just booting -nightly without any display connected on my Bayley Bay B0. Sometimes the 'waiting for the old ack to clear' just times out and I manage to get to the shell, sometimes one of the __raw_i915_read32(dev_priv, FORCEWAKE_ACK_MEDIA_VLV); reads in __vlv_force_wake_get() will hard lock the machine, as in the attached dmesg.
Looks like I can reproduce this too.
We don't reset FORCEWAKE_MEDIA_VLV request register. http://patchwork.freedesktop.org/patch/25693
commit 05adaf1f101f25f40f12c29403e6488f0e45f6b6 Author: Jani Nikula <jani.nikula@intel.com> Date: Fri May 9 14:52:34 2014 +0300 drm/i915/vlv: reset VLV media force wake request register Media force wake get hangs the machine when the system is booted without displays attached. The assumption is that (at least some versions of) the firmware has skipped some initialization in that case. Empirical evidence suggests we need to reset the media force wake request register in addition to the render one to avoid hangs. Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=75895 Reported-by: Imre Deak <imre.deak@intel.com> Reported-by: Darren Hart <dvhart@linux.intel.com> Tested-by: Darren Hart <dvhart@linux.intel.com> Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com> Cc: stable@vger.kernel.org Signed-off-by: Jani Nikula <jani.nikula@intel.com>
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