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)

v3: Avoid unnecessary read when it can be done by reading register once (Chris).

Signed-off-by: Rafael Barbalho <rafael.barba...@intel.com>
Signed-off-by: Arun Siluvery <arun.siluv...@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 8d5932a..dff8303 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -1113,6 +1113,29 @@ static int gen8_init_indirectctx_bb(struct 
intel_engine_cs *ring,
        /* WaDisableCtxRestoreArbitration:bdw,chv */
        wa_ctx_emit(batch, MI_ARB_ON_OFF | MI_ARB_DISABLE);
 
+       /* WaFlushCoherentL3CacheLinesAtContextSwitch:bdw */
+       if (IS_BROADWELL(ring->dev)) {
+               struct drm_i915_private *dev_priv = to_i915(ring->dev);
+               uint32_t l3sqc4_flush = (I915_READ(GEN8_L3SQCREG4) |
+                                        GEN8_LQSC_FLUSH_COHERENT_LINES);
+
+               wa_ctx_emit(batch, MI_LOAD_REGISTER_IMM(1));
+               wa_ctx_emit(batch, GEN8_L3SQCREG4);
+               wa_ctx_emit(batch, l3sqc4_flush);
+
+               wa_ctx_emit(batch, GFX_OP_PIPE_CONTROL(6));
+               wa_ctx_emit(batch, (PIPE_CONTROL_CS_STALL |
+                                   PIPE_CONTROL_DC_FLUSH_ENABLE));
+               wa_ctx_emit(batch, 0);
+               wa_ctx_emit(batch, 0);
+               wa_ctx_emit(batch, 0);
+               wa_ctx_emit(batch, 0);
+
+               wa_ctx_emit(batch, MI_LOAD_REGISTER_IMM(1));
+               wa_ctx_emit(batch, GEN8_L3SQCREG4);
+               wa_ctx_emit(batch, l3sqc4_flush & 
~GEN8_LQSC_FLUSH_COHERENT_LINES);
+       }
+
        /* padding */
         while (((unsigned long) (batch + index) % CACHELINE_BYTES) != 0)
                wa_ctx_emit(batch, MI_NOOP);
-- 
2.3.0

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