drm/i915/cnl: Add Wa_2201832410

"Clock gating bug in GWL may not clear barrier state when an EOT
is received, causing a hang the next time that barrier is used."

HSDES: 2201832410

Cc: Rafael Antognolli <rafael.antognolli@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Rafael Antognolli <rafael.antognolli@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180307220912.3681-1-rodrigo.vivi@intel.com

drivers/gpu/drm/i915/i915_reg.h

@@ -3965,6 +3965,9 @@ enum {
 #define  SARBUNIT_CLKGATE_DIS		(1 << 5)
 #define  RCCUNIT_CLKGATE_DIS		(1 << 7)
 
+#define SUBSLICE_UNIT_LEVEL_CLKGATE	_MMIO(0x9524)
+#define  GWUNIT_CLKGATE_DIS		(1 << 16)
+
 #define UNSLICE_UNIT_LEVEL_CLKGATE	_MMIO(0x9434)
 #define  VFUNIT_CLKGATE_DIS		(1 << 20)
 

drivers/gpu/drm/i915/intel_pm.c

@@ -8522,6 +8522,11 @@ static void cnl_init_clock_gating(struct drm_i915_private *dev_priv)
 		val |= SARBUNIT_CLKGATE_DIS;
 	I915_WRITE(SLICE_UNIT_LEVEL_CLKGATE, val);
 
+	/* Wa_2201832410:cnl */
+	val = I915_READ(SUBSLICE_UNIT_LEVEL_CLKGATE);
+	val |= GWUNIT_CLKGATE_DIS;
+	I915_WRITE(SUBSLICE_UNIT_LEVEL_CLKGATE, val);
+
 	/* WaDisableVFclkgate:cnl */
 	/* WaVFUnitClockGatingDisable:cnl */
 	val = I915_READ(UNSLICE_UNIT_LEVEL_CLKGATE);