drm/i915/gen9: Extend dmc debug mask to include cores

Cores need to be included into the debug mask. We don't exactly
know what it does but the spec says it must be enabled. So obey.

v2: Cores should be only set for BXT (Imre, Art)

Cc: Imre Deak <imre.deak@intel.com>
Cc: Runyan, Arthur J <arthur.j.runyan@intel.com>
Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1455877564-5128-1-git-send-email-mika.kuoppala@intel.com
diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c
index 814cf5a..089701b 100644
--- a/drivers/gpu/drm/i915/intel_runtime_pm.c
+++ b/drivers/gpu/drm/i915/intel_runtime_pm.c
@@ -456,15 +456,19 @@
 	  */
 }
 
-static void gen9_set_dc_state_debugmask_memory_up(
-			struct drm_i915_private *dev_priv)
+static void gen9_set_dc_state_debugmask(struct drm_i915_private *dev_priv)
 {
-	uint32_t val;
+	uint32_t val, mask;
+
+	mask = DC_STATE_DEBUG_MASK_MEMORY_UP;
+
+	if (IS_BROXTON(dev_priv))
+		mask |= DC_STATE_DEBUG_MASK_CORES;
 
 	/* The below bit doesn't need to be cleared ever afterwards */
 	val = I915_READ(DC_STATE_DEBUG);
-	if (!(val & DC_STATE_DEBUG_MASK_MEMORY_UP)) {
-		val |= DC_STATE_DEBUG_MASK_MEMORY_UP;
+	if ((val & mask) != mask) {
+		val |= mask;
 		I915_WRITE(DC_STATE_DEBUG, val);
 		POSTING_READ(DC_STATE_DEBUG);
 	}
@@ -526,7 +530,7 @@
 		state = DC_STATE_EN_UPTO_DC5;
 
 	if (state & DC_STATE_EN_UPTO_DC5_DC6_MASK)
-		gen9_set_dc_state_debugmask_memory_up(dev_priv);
+		gen9_set_dc_state_debugmask(dev_priv);
 
 	val = I915_READ(DC_STATE_EN);
 	DRM_DEBUG_KMS("Setting DC state from %02x to %02x\n",