drm/i915/ringbuffer: Clear semaphore sync registers on ring init
authorChris Wilson <chris@chris-wilson.co.uk>
Mon, 3 Dec 2018 11:36:56 +0000 (11:36 +0000)
committerChris Wilson <chris@chris-wilson.co.uk>
Mon, 3 Dec 2018 12:25:42 +0000 (12:25 +0000)
Ensure that the sync registers are cleared every time we restart the
ring to avoid stale values from creeping in from random neutrinos.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=108888
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181203113701.12106-3-chris@chris-wilson.co.uk
drivers/gpu/drm/i915/intel_ringbuffer.c

index 28ae1e436ea638cb93a302c1152440a16f75c365..d81eaf5f6b3e1e375d752606c1dce3e86f39a955 100644 (file)
@@ -529,6 +529,13 @@ static int init_ring_common(struct intel_engine_cs *engine)
 
        intel_engine_reset_breadcrumbs(engine);
 
+       if (HAS_LEGACY_SEMAPHORES(engine->i915)) {
+               I915_WRITE(RING_SYNC_0(engine->mmio_base), 0);
+               I915_WRITE(RING_SYNC_1(engine->mmio_base), 0);
+               if (HAS_VEBOX(dev_priv))
+                       I915_WRITE(RING_SYNC_2(engine->mmio_base), 0);
+       }
+
        /* Enforce ordering by reading HEAD register back */
        I915_READ_HEAD(engine);