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Commit 1749d90f authored by Chris Wilson's avatar Chris Wilson
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drm/i915: Hold forcewake for the duration of reset+restart



Resetting the engine requires us to hold the forcewake wakeref to
prevent RC6 trying to happen in the middle of the reset sequence. The
consequence of an unwanted RC6 event in the middle is that random state
is then saved to the powercontext and restored later, which may
overwrite the mmio state we need to preserve (e.g. PD_DIR_BASE in the
legacy ringbuffer reset_ring_common()).

This was noticed in the live_hangcheck selftests when Haswell would
sporadically fail to restart during igt_reset_queue().

Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171009110301.21705-3-chris@chris-wilson.co.uk


Reviewed-by: default avatarMika Kuoppala <mika.kuoppala@linux.intel.com>
parent 95a19ab4
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