drm/i915/skl: Implement WaDisableHDCInvalidation

Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Reviewed-by: Nick Hoath <nicholas.hoath@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_reg.h

@@ -140,6 +140,7 @@
 #define GEN8_RING_PDP_LDW(ring, n)	((ring)->mmio_base+0x270 + (n) * 8)
 
 #define GAM_ECOCHK			0x4090
+#define   BDW_DISABLE_HDC_INVALIDATION	(1<<25)
 #define   ECOCHK_SNB_BIT		(1<<10)
 #define   HSW_ECOCHK_ARB_PRIO_SOL	(1<<6)
 #define   ECOCHK_PPGTT_CACHE64B		(0x3<<3)

drivers/gpu/drm/i915/intel_pm.c

@@ -66,6 +66,12 @@ static void skl_init_clock_gating(struct drm_device *dev)
 			   GEN8_SDEUNIT_CLOCK_GATE_DISABLE);
 	}
 
+	if (INTEL_REVID(dev) <= SKL_REVID_D0)
+		/* WaDisableHDCInvalidation:skl */
+		I915_WRITE(GAM_ECOCHK, I915_READ(GAM_ECOCHK) |
+			   BDW_DISABLE_HDC_INVALIDATION);
+
+
 	if (INTEL_REVID(dev) <= SKL_REVID_E0)
 		/* WaDisableLSQCROPERFforOCL:skl */
 		I915_WRITE(GEN8_L3SQCREG4, I915_READ(GEN8_L3SQCREG4) |