drm/i915/gen9: Write dc state debugmask bits only once

DMC debugmask bits should stick so no need to write them
everytime dc state is changed.

v2: Write after firmware has been successfully loaded (Ville)
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/1455808874-22089-5-git-send-email-mika.kuoppala@intel.com

drivers/gpu/drm/i915/intel_csr.c

@@ -220,19 +220,19 @@ static const struct stepping_info *intel_get_stepping_info(struct drm_device *de
  * Everytime display comes back from low power state this function is called to
  * copy the firmware from internal memory to registers.
  */
-void intel_csr_load_program(struct drm_i915_private *dev_priv)
+bool intel_csr_load_program(struct drm_i915_private *dev_priv)
 {
 	u32 *payload = dev_priv->csr.dmc_payload;
 	uint32_t i, fw_size;
 
 	if (!IS_GEN9(dev_priv)) {
 		DRM_ERROR("No CSR support available for this platform\n");
-		return;
+		return false;
 	}
 
 	if (!dev_priv->csr.dmc_payload) {
 		DRM_ERROR("Tried to program CSR with empty payload\n");
-		return;
+		return false;
 	}
 
 	fw_size = dev_priv->csr.dmc_fw_size;
@@ -245,6 +245,8 @@ void intel_csr_load_program(struct drm_i915_private *dev_priv)
 	}
 
 	dev_priv->csr.dc_state = 0;
+
+	return true;
 }
 
 static uint32_t *parse_csr_fw(struct drm_i915_private *dev_priv,

drivers/gpu/drm/i915/intel_drv.h

@@ -1225,7 +1225,7 @@ u32 skl_plane_ctl_rotation(unsigned int rotation);
 
 /* intel_csr.c */
 void intel_csr_ucode_init(struct drm_i915_private *);
-void intel_csr_load_program(struct drm_i915_private *);
+bool intel_csr_load_program(struct drm_i915_private *);
 void intel_csr_ucode_fini(struct drm_i915_private *);
 
 /* intel_dp.c */

drivers/gpu/drm/i915/intel_runtime_pm.c

@@ -529,9 +529,6 @@ static void gen9_set_dc_state(struct drm_i915_private *dev_priv, uint32_t state)
 	else if (i915.enable_dc == 1 && state > DC_STATE_EN_UPTO_DC5)
 		state = DC_STATE_EN_UPTO_DC5;
 
-	if (state & DC_STATE_EN_UPTO_DC5_DC6_MASK)
-		gen9_set_dc_state_debugmask(dev_priv);
-
 	val = I915_READ(DC_STATE_EN);
 	DRM_DEBUG_KMS("Setting DC state from %02x to %02x\n",
 		      val & mask, state);
@@ -2122,8 +2119,8 @@ static void skl_display_core_init(struct drm_i915_private *dev_priv,
 
 	skl_init_cdclk(dev_priv);
 
-	if (dev_priv->csr.dmc_payload)
-		intel_csr_load_program(dev_priv);
+	if (dev_priv->csr.dmc_payload && intel_csr_load_program(dev_priv))
+		gen9_set_dc_state_debugmask(dev_priv);
 }
 
 static void skl_display_core_uninit(struct drm_i915_private *dev_priv)