drm/i915/gen9: Fix DMC firmware initialization

In commit 1e657ad7 we moved the last step of firmware initialization to
skl_display_core_init(), where it will be run only during system resume,
but not during driver loading. Since this init step needs to be done
whenever we program the firmware fix this by moving the initialization
to the end of intel_csr_load_program().

While at it simplify a bit csr_load_work_fn().

This issue prevented DC5/6 transitions, this change will re-enable those.

v2:
- remove debugging left-over and redundant comment in csr_load_work_fn()

Fixes: 1e657ad7 ("drm/i915/gen9: Write dc state debugmask bits only once")
CC: Mika Kuoppala <mika.kuoppala@intel.com>
CC: Patrik Jakobsson <patrik.jakobsson@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1457121461-16729-1-git-send-email-imre.deak@intel.com

drivers/gpu/drm/i915/intel_csr.c

@@ -212,6 +212,24 @@ static const struct stepping_info *intel_get_stepping_info(struct drm_device *de
 	return NULL;
 }
 
+static void gen9_set_dc_state_debugmask(struct drm_i915_private *dev_priv)
+{
+	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 & mask) != mask) {
+		val |= mask;
+		I915_WRITE(DC_STATE_DEBUG, val);
+		POSTING_READ(DC_STATE_DEBUG);
+	}
+}
+
 /**
  * intel_csr_load_program() - write the firmware from memory to register.
  * @dev_priv: i915 drm device.
@@ -220,19 +238,19 @@ 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.
  */
-bool intel_csr_load_program(struct drm_i915_private *dev_priv)
+void 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 false;
+		return;
 	}
 
 	if (!dev_priv->csr.dmc_payload) {
 		DRM_ERROR("Tried to program CSR with empty payload\n");
-		return false;
+		return;
 	}
 
 	fw_size = dev_priv->csr.dmc_fw_size;
@@ -246,7 +264,7 @@ bool intel_csr_load_program(struct drm_i915_private *dev_priv)
 
 	dev_priv->csr.dc_state = 0;
 
-	return true;
+	gen9_set_dc_state_debugmask(dev_priv);
 }
 
 static uint32_t *parse_csr_fw(struct drm_i915_private *dev_priv,
@@ -388,18 +406,12 @@ static void csr_load_work_fn(struct work_struct *work)
 
 	ret = request_firmware(&fw, dev_priv->csr.fw_path,
 			       &dev_priv->dev->pdev->dev);
-	if (!fw)
-		goto out;
+	if (fw)
+		dev_priv->csr.dmc_payload = parse_csr_fw(dev_priv, fw);
 
-	dev_priv->csr.dmc_payload = parse_csr_fw(dev_priv, fw);
-	if (!dev_priv->csr.dmc_payload)
-		goto out;
-
-	/* load csr program during system boot, as needed for DC states */
-	intel_csr_load_program(dev_priv);
-
-out:
 	if (dev_priv->csr.dmc_payload) {
+		intel_csr_load_program(dev_priv);
+
 		intel_display_power_put(dev_priv, POWER_DOMAIN_INIT);
 
 		DRM_INFO("Finished loading %s (v%u.%u)\n",

drivers/gpu/drm/i915/intel_drv.h

@@ -1279,7 +1279,7 @@ u32 skl_plane_ctl_rotation(unsigned int rotation);
 
 /* intel_csr.c */
 void intel_csr_ucode_init(struct drm_i915_private *);
-bool intel_csr_load_program(struct drm_i915_private *);
+void 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

@@ -470,24 +470,6 @@ static void assert_can_disable_dc9(struct drm_i915_private *dev_priv)
 	  */
 }
 
-static void gen9_set_dc_state_debugmask(struct drm_i915_private *dev_priv)
-{
-	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 & mask) != mask) {
-		val |= mask;
-		I915_WRITE(DC_STATE_DEBUG, val);
-		POSTING_READ(DC_STATE_DEBUG);
-	}
-}
-
 static void gen9_write_dc_state(struct drm_i915_private *dev_priv,
 				u32 state)
 {
@@ -2141,8 +2123,8 @@ 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))
-		gen9_set_dc_state_debugmask(dev_priv);
+	if (dev_priv->csr.dmc_payload)
+		intel_csr_load_program(dev_priv);
 }
 
 static void skl_display_core_uninit(struct drm_i915_private *dev_priv)