drm/i915/gen9: Fix DMC/DC state asserts

The display power well support and DC state management doesn't depend on
runtime PM support, so remove the incorrect asserts about this.

Also Broxton does support DC5, so the related assert in
assert_can_enable_dc5() is incorrect. There is a more generic and
correct assert for this already in gen9_set_dc_state(), so we can remove
all the other ones.

At the same time convert WARNs to WARN_ONCE for consistency with the
other DC state asserts.

CC: Patrik Jakobsson <patrik.jakobsson@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Patrik Jakobsson <patrik.jakobsson@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1459515767-29228-7-git-send-email-imre.deak@intel.com

drivers/gpu/drm/i915/intel_runtime_pm.c

@@ -443,15 +443,13 @@ static void hsw_set_power_well(struct drm_i915_private *dev_priv,
 
 static void assert_can_enable_dc9(struct drm_i915_private *dev_priv)
 {
-	struct drm_device *dev = dev_priv->dev;
-
-	WARN(!IS_BROXTON(dev), "Platform doesn't support DC9.\n");
-	WARN((I915_READ(DC_STATE_EN) & DC_STATE_EN_DC9),
+	WARN_ONCE((I915_READ(DC_STATE_EN) & DC_STATE_EN_DC9),
 		  "DC9 already programmed to be enabled.\n");
-	WARN(I915_READ(DC_STATE_EN) & DC_STATE_EN_UPTO_DC5,
+	WARN_ONCE(I915_READ(DC_STATE_EN) & DC_STATE_EN_UPTO_DC5,
 		  "DC5 still not disabled to enable DC9.\n");
-	WARN(I915_READ(HSW_PWR_WELL_DRIVER), "Power well on.\n");
-	WARN(intel_irqs_enabled(dev_priv), "Interrupts not disabled yet.\n");
+	WARN_ONCE(I915_READ(HSW_PWR_WELL_DRIVER), "Power well on.\n");
+	WARN_ONCE(intel_irqs_enabled(dev_priv),
+		  "Interrupts not disabled yet.\n");
 
 	 /*
 	  * TODO: check for the following to verify the conditions to enter DC9
@@ -464,8 +462,9 @@ static void assert_can_enable_dc9(struct drm_i915_private *dev_priv)
 
 static void assert_can_disable_dc9(struct drm_i915_private *dev_priv)
 {
-	WARN(intel_irqs_enabled(dev_priv), "Interrupts not disabled yet.\n");
-	WARN(I915_READ(DC_STATE_EN) & DC_STATE_EN_UPTO_DC5,
+	WARN_ONCE(intel_irqs_enabled(dev_priv),
+		  "Interrupts not disabled yet.\n");
+	WARN_ONCE(I915_READ(DC_STATE_EN) & DC_STATE_EN_UPTO_DC5,
 		  "DC5 still not disabled.\n");
 
 	 /*
@@ -573,13 +572,9 @@ static void assert_csr_loaded(struct drm_i915_private *dev_priv)
 
 static void assert_can_enable_dc5(struct drm_i915_private *dev_priv)
 {
-	struct drm_device *dev = dev_priv->dev;
 	bool pg2_enabled = intel_display_power_well_is_enabled(dev_priv,
 					SKL_DISP_PW_2);
 
-	WARN_ONCE(!IS_SKYLAKE(dev) && !IS_KABYLAKE(dev),
-		  "Platform doesn't support DC5.\n");
-	WARN_ONCE(!HAS_RUNTIME_PM(dev), "Runtime PM not enabled.\n");
 	WARN_ONCE(pg2_enabled, "PG2 not disabled to enable DC5.\n");
 
 	WARN_ONCE((I915_READ(DC_STATE_EN) & DC_STATE_EN_UPTO_DC5),
@@ -600,11 +595,6 @@ static void gen9_enable_dc5(struct drm_i915_private *dev_priv)
 
 static void assert_can_enable_dc6(struct drm_i915_private *dev_priv)
 {
-	struct drm_device *dev = dev_priv->dev;
-
-	WARN_ONCE(!IS_SKYLAKE(dev) && !IS_KABYLAKE(dev),
-		  "Platform doesn't support DC6.\n");
-	WARN_ONCE(!HAS_RUNTIME_PM(dev), "Runtime PM not enabled.\n");
 	WARN_ONCE(I915_READ(UTIL_PIN_CTL) & UTIL_PIN_ENABLE,
 		  "Backlight is not disabled.\n");
 	WARN_ONCE((I915_READ(DC_STATE_EN) & DC_STATE_EN_UPTO_DC6),