[PATCH 3/5] drm/i915: WaInsertNoopAfterBatchEndCommand

[Daniel Vetter <daniel.vetter@ffwll.ch>]

Comment says that this applies to earlier gens, too. Since two more
MI_NOOP's can't hurt that much, I've figured I'll apply this w/a down
to gen2.

v2: Correct the ringbuffer dword count for gen3, spotted by Chris
Wilson.

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
---
 drivers/gpu/drm/i915/intel_ringbuffer.c |   18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 984a0c5..38092dc 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -969,7 +969,7 @@ i965_dispatch_execbuffer(struct intel_ring_buffer *ring, u32 offset, u32 length)
 {
 	int ret;
 
-	ret = intel_ring_begin(ring, 2);
+	ret = intel_ring_begin(ring, 4);
 	if (ret)
 		return ret;
 
@@ -978,6 +978,11 @@ i965_dispatch_execbuffer(struct intel_ring_buffer *ring, u32 offset, u32 length)
 			MI_BATCH_GTT |
 			MI_BATCH_NON_SECURE_I965);
 	intel_ring_emit(ring, offset);
+	/* WaInsertNoopAfterBatchEndCommand: Command says to do the same after
+	 * the batchbuffer start command. Unclear whether really required on
+	 * gen3, but better safe than sorry. */
+	intel_ring_emit(ring, MI_NOOP);
+	intel_ring_emit(ring, MI_NOOP);
 	intel_ring_advance(ring);
 
 	return 0;
@@ -996,7 +1001,10 @@ i830_dispatch_execbuffer(struct intel_ring_buffer *ring,
 	intel_ring_emit(ring, MI_BATCH_BUFFER);
 	intel_ring_emit(ring, offset | MI_BATCH_NON_SECURE);
 	intel_ring_emit(ring, offset + len - 8);
-	intel_ring_emit(ring, 0);
+	/* WaInsertNoopAfterBatchEndCommand: Command says to do the same after
+	 * the batchbuffer start command. Unclear whether really required on
+	 * gen2, but better safe than sorry. */
+	intel_ring_emit(ring, MI_NOOP);
 	intel_ring_advance(ring);
 
 	return 0;
@@ -1008,12 +1016,16 @@ i915_dispatch_execbuffer(struct intel_ring_buffer *ring,
 {
 	int ret;
 
-	ret = intel_ring_begin(ring, 2);
+	ret = intel_ring_begin(ring, 4);
 	if (ret)
 		return ret;
 
 	intel_ring_emit(ring, MI_BATCH_BUFFER_START | MI_BATCH_GTT);
 	intel_ring_emit(ring, offset | MI_BATCH_NON_SECURE);
+	/* WaInsertNoopAfterBatchEndCommand: Command says to do the same after
+	 * the batchbuffer start command. */
+	intel_ring_emit(ring, MI_NOOP);
+	intel_ring_emit(ring, MI_NOOP);
 	intel_ring_advance(ring);
 
 	return 0;
-- 
1.7.10.4