3 files changed, 22 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
index d49d5fc0a59..fb1e1d22572 100644
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -324,6 +324,17 @@ mi_set_context(struct intel_ring_buffer *ring,
 {
 	int ret;
 
+	/* w/a: If Flush TLB Invalidation Mode is enabled, driver must do a TLB
+	 * invalidation prior to MI_SET_CONTEXT. On GEN6 we don't set the value
+	 * explicitly, so we rely on the value at ring init, stored in
+	 * itlb_before_ctx_switch.
+	 */
+	if (IS_GEN6(ring->dev) && ring->itlb_before_ctx_switch) {
+		ret = ring->flush(ring, 0, 0);
+		if (ret)
+			return ret;
+	}
+
 	ret = intel_ring_begin(ring, 6);
 	if (ret)
 		return ret;
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index a041492fdd4..7a16f16371e 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -423,6 +423,13 @@ static int init_render_ring(struct intel_ring_buffer *ring)
 		 */
 		I915_WRITE(CACHE_MODE_0,
 			   _MASKED_BIT_DISABLE(CM0_STC_EVICT_DISABLE_LRA_SNB));
+
+		/* This is not explicitly set for GEN6, so read the register.
+		 * see intel_ring_mi_set_context() for why we care.
+		 * TODO: consider explicitly setting the bit for GEN5
+		 */
+		ring->itlb_before_ctx_switch =
+			!!(I915_READ(GFX_MODE) & GFX_TLB_INVALIDATE_ALWAYS);
 	}
 
 	if (INTEL_INFO(dev)->gen >= 6)
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index b7884b90474..594c9c4ad39 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -116,6 +116,10 @@ struct  intel_ring_buffer {
 
 	wait_queue_head_t irq_queue;
 
+	/**
+	 * Do an explicit TLB flush before MI_SET_CONTEXT
+	 */
+	bool itlb_before_ctx_switch;
 	struct i915_hw_context *default_context;
 	struct drm_i915_gem_object *last_context_obj;