drm/i915: fix WaInsertDummyPushConstPs

As pointed out by Chris Harris, we are using the wrong WA name, it
should in fact be WaToEnableHwFixForPushConstHWBug, also it should be
applied from C0 onwards for both BXT and KBL.

Fixes: 7b9005cd ("drm/i915: Add WaInsertDummyPushConstP for bxt and kbl")

Cc: Chris Harris <chris.harris@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Reported-by: NChris Harris <chris.harris@intel.com>
Signed-off-by: NMatthew Auld <matthew.auld@intel.com>
Reviewed-by: NArun Siluvery <arun.siluvery@linux.intel.com>
Signed-off-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470127013-29653-1-git-send-email-matthew.auld@intel.com
(cherry picked from commit 575e3ccb)
Signed-off-by: NJani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/intel_ringbuffer.c

@@ -1178,8 +1178,8 @@ static int bxt_init_workarounds(struct intel_engine_cs *engine)
 		I915_WRITE(GEN8_L3SQCREG1, L3_GENERAL_PRIO_CREDITS(62) |
 					   L3_HIGH_PRIO_CREDITS(2));
 
-	/* WaInsertDummyPushConstPs:bxt */
-	if (IS_BXT_REVID(dev_priv, 0, BXT_REVID_B0))
+	/* WaToEnableHwFixForPushConstHWBug:bxt */
+	if (IS_BXT_REVID(dev_priv, BXT_REVID_C0, REVID_FOREVER))
 		WA_SET_BIT_MASKED(COMMON_SLICE_CHICKEN2,
 				  GEN8_SBE_DISABLE_REPLAY_BUF_OPTIMIZATION);
 
@@ -1222,8 +1222,8 @@ static int kbl_init_workarounds(struct intel_engine_cs *engine)
 		I915_WRITE(GEN8_L3SQCREG4, I915_READ(GEN8_L3SQCREG4) |
 			   GEN8_LQSC_RO_PERF_DIS);
 
-	/* WaInsertDummyPushConstPs:kbl */
-	if (IS_KBL_REVID(dev_priv, 0, KBL_REVID_B0))
+	/* WaToEnableHwFixForPushConstHWBug:kbl */
+	if (IS_KBL_REVID(dev_priv, KBL_REVID_C0, REVID_FOREVER))
 		WA_SET_BIT_MASKED(COMMON_SLICE_CHICKEN2,
 				  GEN8_SBE_DISABLE_REPLAY_BUF_OPTIMIZATION);