[Intel-gfx] [PATCH v2 3/4] drm/i915/gen9: Add WaFlushCoherentL3CacheLinesAtContextSwitch workaround

[Arun Siluvery]

In Indirect context w/a batch buffer,
+WaFlushCoherentL3CacheLinesAtContextSwitch:bdw

v2: address static checker warning where unsigned value was checked for
less than zero which is never true.

Reported-by: Dan Carpenter <dan.carpenter at oracle.com>
Cc: Imre Deak <imre.deak at intel.com>
Signed-off-by: Arun Siluvery <arun.siluvery at linux.intel.com>
---
 drivers/gpu/drm/i915/intel_lrc.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 6a0b128..7536682 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -1253,6 +1253,7 @@ static int gen9_init_indirectctx_bb(struct intel_engine_cs *ring,
 				    uint32_t *const batch,
 				    uint32_t *offset)
 {
+	int ret;
 	struct drm_device *dev = ring->dev;
 	uint32_t index = wa_ctx_start(wa_ctx, *offset, CACHELINE_DWORDS);
 
@@ -1261,6 +1262,12 @@ static int gen9_init_indirectctx_bb(struct intel_engine_cs *ring,
 	    (IS_BROXTON(dev) && (INTEL_REVID(dev) == BXT_REVID_A0)))
 		wa_ctx_emit(batch, MI_ARB_ON_OFF | MI_ARB_DISABLE);
 
+	/* WaFlushCoherentL3CacheLinesAtContextSwitch:skl,bxt */
+	ret = gen8_emit_flush_coherentl3_wa(ring, batch, index);
+	if (ret < 0)
+		return ret;
+	index = ret;
+
 	/* Pad to end of cacheline */
 	while (index % CACHELINE_DWORDS)
 		wa_ctx_emit(batch, MI_NOOP);
-- 
1.9.1