drm/i915/chv: Implement WaDisableShadowRegForCpd

This WA is avoid problem between shadow vs wake FIFO unload
problem during CPD/RC6 transactions on CHV.

v2: Define individual bits GTFIFOCTL (Ville)

v3: move WA to uncore_early_sanitize (ville)
Signed-off-by: Deepak S <deepak.s@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
[Jani: fixed some whitespace issues while applying]
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/i915_reg.h

@@ -6074,6 +6074,8 @@ enum skl_disp_power_wells {
 #define  GTFIFOCTL				0x120008
 #define    GT_FIFO_FREE_ENTRIES_MASK		0x7f
 #define    GT_FIFO_NUM_RESERVED_ENTRIES		20
+#define    GT_FIFO_CTL_BLOCK_ALL_POLICY_STALL	(1 << 12)
+#define    GT_FIFO_CTL_RC6_POLICY_STALL		(1 << 11)
 
 #define  HSW_IDICR				0x9008
 #define    IDIHASHMSK(x)			(((x) & 0x3f) << 16)

drivers/gpu/drm/i915/intel_uncore.c

@@ -360,6 +360,14 @@ static void __intel_uncore_early_sanitize(struct drm_device *dev,
 		__raw_i915_write32(dev_priv, GTFIFODBG,
 				   __raw_i915_read32(dev_priv, GTFIFODBG));
 
+	/* WaDisableShadowRegForCpd:chv */
+	if (IS_CHERRYVIEW(dev)) {
+		__raw_i915_write32(dev_priv, GTFIFOCTL,
+				   __raw_i915_read32(dev_priv, GTFIFOCTL) |
+				   GT_FIFO_CTL_BLOCK_ALL_POLICY_STALL |
+				   GT_FIFO_CTL_RC6_POLICY_STALL);
+	}
+
 	intel_uncore_forcewake_reset(dev, restore_forcewake);
 }