Commit f42bb651 authored Apr 11, 2017 by Chris Wilson

drm/i915: Use safer intel_uncore_wait_for_register in ring-init

While we do hold the forcewake for legacy ringbuffer initialisation, we
don't guard our access with the uncore.lock spinlock. In theory, we only
initialise when no others should be accessing the same mmio cachelines,
but in practice be safe as this is an infrequently used path and not
worth risky micro-optimisations.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170411101340.31994-5-chris@chris-wilson.co.uk

Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

parent e09a3036

drivers/gpu/drm/i915/intel_ringbuffer.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -538,7 +538,7 @@ static int init_ring_common(struct intel_engine_cs *engine)
		I915_WRITE_CTL(engine, RING_CTL_SIZE(ring->size) \| RING_VALID);

		/* If the head is still not zero, the ring is dead */
		if (intel_wait_for_register_fw(dev_priv, RING_CTL(engine->mmio_base),
		if (intel_wait_for_register(dev_priv, RING_CTL(engine->mmio_base),
		RING_VALID, RING_VALID,
		50)) {
		DRM_ERROR("%s initialization failed "