[Intel-gfx] [PATCH v4 4/6] drm/i915/gen8: Add WaFlushCoherentL3CacheLinesAtContextSwitch workaround

[Arun Siluvery]

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

v2: Add LRI commands to set/reset bit that invalidates coherent lines,
update WA to include programming restrictions and exclude CHV as
it is not required (Ville)

Signed-off-by: Rafael Barbalho <rafael.barbalho at intel.com>
Signed-off-by: Arun Siluvery <arun.siluvery at linux.intel.com>
---
 drivers/gpu/drm/i915/i915_reg.h  |  2 ++
 drivers/gpu/drm/i915/intel_lrc.c | 23 +++++++++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 84af255..d14ad20 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -426,6 +426,7 @@
 #define   PIPE_CONTROL_INDIRECT_STATE_DISABLE		(1<<9)
 #define   PIPE_CONTROL_NOTIFY				(1<<8)
 #define   PIPE_CONTROL_FLUSH_ENABLE			(1<<7) /* gen7+ */
+#define   PIPE_CONTROL_DC_FLUSH_ENABLE			(1<<5)
 #define   PIPE_CONTROL_VF_CACHE_INVALIDATE		(1<<4)
 #define   PIPE_CONTROL_CONST_CACHE_INVALIDATE		(1<<3)
 #define   PIPE_CONTROL_STATE_CACHE_INVALIDATE		(1<<2)
@@ -5788,6 +5789,7 @@ enum skl_disp_power_wells {
 
 #define GEN8_L3SQCREG4				0xb118
 #define  GEN8_LQSC_RO_PERF_DIS			(1<<27)
+#define  GEN8_LQSC_FLUSH_COHERENT_LINES		(1<<21)
 
 /* GEN8 chicken */
 #define HDC_CHICKEN0				0x7300
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index c9875f6..92556b9 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -1094,6 +1094,29 @@ static int gen8_init_indirectctx_bb(struct intel_engine_cs *ring,
 	/* WaDisableCtxRestoreArbitration:bdw,chv */
 	cmd[index++] = MI_ARB_ON_OFF | MI_ARB_DISABLE;
 
+	/* WaFlushCoherentL3CacheLinesAtContextSwitch:bdw */
+	if (IS_BROADWELL(ring->dev)) {
+		struct drm_i915_private *dev_priv = ring->dev->dev_private;
+
+		cmd[index++] = MI_LOAD_REGISTER_IMM(1);
+		cmd[index++] = GEN8_L3SQCREG4;
+		cmd[index++] = I915_READ(GEN8_L3SQCREG4) |
+			GEN8_LQSC_FLUSH_COHERENT_LINES;
+
+		cmd[index++] = GFX_OP_PIPE_CONTROL(6);
+		cmd[index++] = PIPE_CONTROL_CS_STALL |
+			PIPE_CONTROL_DC_FLUSH_ENABLE;
+		cmd[index++] = 0;
+		cmd[index++] = 0;
+		cmd[index++] = 0;
+		cmd[index++] = 0;
+
+		cmd[index++] = MI_LOAD_REGISTER_IMM(1);
+		cmd[index++] = GEN8_L3SQCREG4;
+		cmd[index++] = I915_READ(GEN8_L3SQCREG4) &
+			~GEN8_LQSC_FLUSH_COHERENT_LINES;
+	}
+
 	/* padding */
         while (((unsigned long) (cmd + index) % CACHELINE_BYTES) != 0)
 		cmd[index++] = MI_NOOP;
-- 
2.3.0