drm/i915: Perform a central cdclk state sanity check

WARN if the cdclk state doesn't match what we expect after programming.
And let's remove the WARN from bdw_set_cdclk() that's trying to achieve
the same thing in a more limite fashion.

Also take the opportunity to refactor the code to use a common function
for dumping out a cdclk state.

Cc: Mika Kahola <mika.kahola@intel.com>
Cc: Manasi Navare <manasi.d.navare@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171024095216.1638-11-ville.syrjala@linux.intel.com
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

drivers/gpu/drm/i915/intel_cdclk.c

@@ -768,10 +768,6 @@ static void bdw_set_cdclk(struct drm_i915_private *dev_priv,
 	I915_WRITE(CDCLK_FREQ, DIV_ROUND_CLOSEST(cdclk, 1000) - 1);
 
 	intel_update_cdclk(dev_priv);
-
-	WARN(cdclk != dev_priv->cdclk.hw.cdclk,
-	     "cdclk requested %d kHz but got %d kHz\n",
-	     cdclk, dev_priv->cdclk.hw.cdclk);
 }
 
 static int skl_calc_cdclk(int min_cdclk, int vco)
@@ -1068,6 +1064,8 @@ static void skl_sanitize_cdclk(struct drm_i915_private *dev_priv)
 		goto sanitize;
 
 	intel_update_cdclk(dev_priv);
+	intel_dump_cdclk_state(&dev_priv->cdclk.hw, "Current CDCLK");
+
 	/* Is PLL enabled and locked ? */
 	if (dev_priv->cdclk.hw.vco == 0 ||
 	    dev_priv->cdclk.hw.cdclk == dev_priv->cdclk.hw.ref)
@@ -1407,6 +1405,7 @@ static void bxt_sanitize_cdclk(struct drm_i915_private *dev_priv)
 	u32 cdctl, expected;
 
 	intel_update_cdclk(dev_priv);
+	intel_dump_cdclk_state(&dev_priv->cdclk.hw, "Current CDCLK");
 
 	if (dev_priv->cdclk.hw.vco == 0 ||
 	    dev_priv->cdclk.hw.cdclk == dev_priv->cdclk.hw.ref)
@@ -1713,6 +1712,7 @@ static void cnl_sanitize_cdclk(struct drm_i915_private *dev_priv)
 	u32 cdctl, expected;
 
 	intel_update_cdclk(dev_priv);
+	intel_dump_cdclk_state(&dev_priv->cdclk.hw, "Current CDCLK");
 
 	if (dev_priv->cdclk.hw.vco == 0 ||
 	    dev_priv->cdclk.hw.cdclk == dev_priv->cdclk.hw.ref)
@@ -1826,6 +1826,14 @@ bool intel_cdclk_changed(const struct intel_cdclk_state *a,
 		a->voltage_level != b->voltage_level;
 }
 
+void intel_dump_cdclk_state(const struct intel_cdclk_state *cdclk_state,
+			    const char *context)
+{
+	DRM_DEBUG_DRIVER("%s %d kHz, VCO %d kHz, ref %d kHz, voltage level %d\n",
+			 context, cdclk_state->cdclk, cdclk_state->vco,
+			 cdclk_state->ref, cdclk_state->voltage_level);
+}
+
 /**
  * intel_set_cdclk - Push the CDCLK state to the hardware
  * @dev_priv: i915 device
@@ -1843,11 +1851,15 @@ void intel_set_cdclk(struct drm_i915_private *dev_priv,
 	if (WARN_ON_ONCE(!dev_priv->display.set_cdclk))
 		return;
 
-	DRM_DEBUG_DRIVER("Changing CDCLK to %d kHz, VCO %d kHz, ref %d kHz, voltage_level %d\n",
-			 cdclk_state->cdclk, cdclk_state->vco,
-			 cdclk_state->ref, cdclk_state->voltage_level);
+	intel_dump_cdclk_state(cdclk_state, "Changing CDCLK to");
 
 	dev_priv->display.set_cdclk(dev_priv, cdclk_state);
+
+	if (WARN(intel_cdclk_changed(&dev_priv->cdclk.hw, cdclk_state),
+		 "cdclk state doesn't match!\n")) {
+		intel_dump_cdclk_state(&dev_priv->cdclk.hw, "[hw state]");
+		intel_dump_cdclk_state(cdclk_state, "[sw state]");
+	}
 }
 
 static int intel_pixel_rate_to_cdclk(struct drm_i915_private *dev_priv,
@@ -2280,10 +2292,6 @@ void intel_update_cdclk(struct drm_i915_private *dev_priv)
 {
 	dev_priv->display.get_cdclk(dev_priv, &dev_priv->cdclk.hw);
 
-	DRM_DEBUG_DRIVER("Current CD clock rate: %d kHz, VCO: %d kHz, ref: %d kHz\n",
-			 dev_priv->cdclk.hw.cdclk, dev_priv->cdclk.hw.vco,
-			 dev_priv->cdclk.hw.ref);
-
 	/*
 	 * 9:0 CMBUS [sic] CDCLK frequency (cdfreq):
 	 * Programmng [sic] note: bit[9:2] should be programmed to the number

drivers/gpu/drm/i915/intel_display.c

@@ -8857,7 +8857,9 @@ static void hsw_restore_lcpll(struct drm_i915_private *dev_priv)
 	}
 
 	intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL);
+
 	intel_update_cdclk(dev_priv);
+	intel_dump_cdclk_state(&dev_priv->cdclk.hw, "Current CDCLK");
 }
 
 /*
@@ -14358,6 +14360,7 @@ void intel_modeset_init_hw(struct drm_device *dev)
 	struct drm_i915_private *dev_priv = to_i915(dev);
 
 	intel_update_cdclk(dev_priv);
+	intel_dump_cdclk_state(&dev_priv->cdclk.hw, "Current CDCLK");
 	dev_priv->cdclk.logical = dev_priv->cdclk.actual = dev_priv->cdclk.hw;
 
 	intel_init_clock_gating(dev_priv);

drivers/gpu/drm/i915/intel_drv.h

@@ -1336,6 +1336,8 @@ bool intel_cdclk_changed(const struct intel_cdclk_state *a,
 			 const struct intel_cdclk_state *b);
 void intel_set_cdclk(struct drm_i915_private *dev_priv,
 		     const struct intel_cdclk_state *cdclk_state);
+void intel_dump_cdclk_state(const struct intel_cdclk_state *cdclk_state,
+			    const char *context);
 
 /* intel_display.c */
 void i830_enable_pipe(struct drm_i915_private *dev_priv, enum pipe pipe);