[Intel-gfx] [PATCH v2 1/3] drm/i915/vlv: Added a rendering specific Hw WA 'WaTlbInvalidateStoreDataBefore'

[akash.goel at intel.com]

From: Akash Goel <akash.goel at intel.com>

Added a new rendering specific Workaround 'WaTlbInvalidateStoreDataBefore'.
In this WA, before pipecontrol with TLB invalidate set, need to add 2 MI
Store data commands.

v2: Modified the WA comment. (Ville)

Signed-off-by: Akash Goel <akash.goel at intel.com>
---
 drivers/gpu/drm/i915/intel_ringbuffer.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index d897a19..2ac6600 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -2183,6 +2183,29 @@ intel_ring_invalidate_all_caches(struct intel_ring_buffer *ring)
 	uint32_t flush_domains;
 	int ret;
 
+	if (IS_VALLEYVIEW(ring->dev)) {
+		/*
+		 * WaTlbInvalidateStoreDataBefore
+		 * Before pipecontrol with TLB invalidate set, need 2 store
+		 * data commands (such as MI_STORE_DATA_IMM or MI_STORE_DATA_INDEX)
+		 * Without this, hardware cannot guarantee the command after the
+		 * PIPE_CONTROL with TLB inv will not use the old TLB values.
+		 * FIXME, should also apply to snb, ivb
+		 */
+		int i;
+		ret = intel_ring_begin(ring, 4 * 2);
+		if (ret)
+			return ret;
+		for (i = 0; i < 2; i++) {
+			intel_ring_emit(ring, MI_STORE_DWORD_INDEX);
+			intel_ring_emit(ring, I915_GEM_HWS_SCRATCH_INDEX <<
+						MI_STORE_DWORD_INDEX_SHIFT);
+			intel_ring_emit(ring, 0);
+			intel_ring_emit(ring, MI_NOOP);
+		}
+		intel_ring_advance(ring);
+	}
+
 	flush_domains = 0;
 	if (ring->gpu_caches_dirty)
 		flush_domains = I915_GEM_GPU_DOMAINS;
-- 
1.8.5.2