drm/i915: Acquire uncore.lock over intel_uncore_wait_for_register()
We acquire the forcewake and use I915_READ_FW instead for the atomic wait within intel_uncore_wait_for_register. However, this still leaves us vulnerable to concurrent mmio access to the register, which can cause system hangs on gen7. The protection is to acquire uncore.lock around each register, so lets add it back. v2: Wrap __intel_wait_for_register_fw() to re-use its atomic wait_for loop and spare adding another for ourselves. v3: Add might_sleep() annotation Signed-off-by:Chris Wilson <chris@chris-wilson.co.uk> Cc: Michal Wajdeczko <michal.wajdeczko@intel.com> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/20170411101340.31994-3-chris@chris-wilson.co.uk Reviewed-by:
Tvrtko Ursulin <tvrtko.ursulin@intel.com>
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02b312d0
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