drm/i915/skl: Default to noncoherent access up to F0

The workarounds for disabling hdc invalidation and also forcing
context to be non coherent, are advised to be used up until rev D0.

However as it was found that rev F0, without the
WaForceEnableNonCoherent might system hang if the mesa
tried to use coherent mode.

As these two workarounds are about non coherent access, are
grouped in scope and they point the same HSD, increase the
scope of both to set default behaviour to non coherent access.

References: HSD: gen9lp/2131413
References: http://lists.freedesktop.org/archives/mesa-dev/2015-November/101515.html
Cc: Ben Widawsky <benjamin.widawsky@intel.com>
Cc: Francisco Jerez <currojerez@riseup.net>
Reviewed-by: NFrancisco Jerez <currojerez@riseup.net>
Signed-off-by: NMika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1450448093-22906-1-git-send-email-mika.kuoppala@intel.com

drivers/gpu/drm/i915/intel_ringbuffer.c

@@ -1018,10 +1018,6 @@ static int skl_init_workarounds(struct intel_engine_cs *ring)
 		return ret;
 
 	if (IS_SKL_REVID(dev, 0, SKL_REVID_D0)) {
-		/* WaDisableHDCInvalidation:skl */
-		I915_WRITE(GAM_ECOCHK, I915_READ(GAM_ECOCHK) |
-			   BDW_DISABLE_HDC_INVALIDATION);
-
 		/* WaDisableChickenBitTSGBarrierAckForFFSliceCS:skl */
 		I915_WRITE(FF_SLICE_CS_CHICKEN2,
 			   _MASKED_BIT_ENABLE(GEN9_TSG_BARRIER_ACK_DISABLE));
@@ -1046,7 +1042,7 @@ static int skl_init_workarounds(struct intel_engine_cs *ring)
 		WA_SET_BIT_MASKED(HIZ_CHICKEN,
 				  BDW_HIZ_POWER_COMPILER_CLOCK_GATING_DISABLE);
 
-	if (IS_SKL_REVID(dev, 0, SKL_REVID_D0)) {
+	if (IS_SKL_REVID(dev, 0, SKL_REVID_F0)) {
 		/*
 		 *Use Force Non-Coherent whenever executing a 3D context. This
 		 * is a workaround for a possible hang in the unlikely event
@@ -1055,6 +1051,10 @@ static int skl_init_workarounds(struct intel_engine_cs *ring)
 		/* WaForceEnableNonCoherent:skl */
 		WA_SET_BIT_MASKED(HDC_CHICKEN0,
 				  HDC_FORCE_NON_COHERENT);
+
+		/* WaDisableHDCInvalidation:skl */
+		I915_WRITE(GAM_ECOCHK, I915_READ(GAM_ECOCHK) |
+			   BDW_DISABLE_HDC_INVALIDATION);
 	}
 
 	/* WaBarrierPerformanceFixDisable:skl */