drm/i915: Emit SRM after the MSG_FBC_REND_STATE LRI

The spec tells us that we need to emit an SRM after the LRI
to MSG_FBC_REND_STATE.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_reg.h

@@ -235,6 +235,7 @@
  */
 #define MI_LOAD_REGISTER_IMM(x)	MI_INSTR(0x22, 2*x-1)
 #define MI_STORE_REGISTER_MEM(x) MI_INSTR(0x24, 2*x-1)
+#define  MI_SRM_LRM_GLOBAL_GTT		(1<<22)
 #define MI_FLUSH_DW		MI_INSTR(0x26, 1) /* for GEN6 */
 #define   MI_FLUSH_DW_STORE_INDEX	(1<<21)
 #define   MI_INVALIDATE_TLB		(1<<18)

drivers/gpu/drm/i915/intel_ringbuffer.c

@@ -285,14 +285,16 @@ static int gen7_ring_fbc_flush(struct intel_ring_buffer *ring, u32 value)
 	if (!ring->fbc_dirty)
 		return 0;
 
-	ret = intel_ring_begin(ring, 4);
+	ret = intel_ring_begin(ring, 6);
 	if (ret)
 		return ret;
-	intel_ring_emit(ring, MI_NOOP);
 	/* WaFbcNukeOn3DBlt:ivb/hsw */
 	intel_ring_emit(ring, MI_LOAD_REGISTER_IMM(1));
 	intel_ring_emit(ring, MSG_FBC_REND_STATE);
 	intel_ring_emit(ring, value);
+	intel_ring_emit(ring, MI_STORE_REGISTER_MEM(1) | MI_SRM_LRM_GLOBAL_GTT);
+	intel_ring_emit(ring, MSG_FBC_REND_STATE);
+	intel_ring_emit(ring, ring->scratch.gtt_offset + 256);
 	intel_ring_advance(ring);
 
 	ring->fbc_dirty = false;