drm/i915: Cache current cdclk frequency in dev_priv

Rather that extracting the current cdclk freuqncy every time someone
wants to know it, cache the current value and use that. VLV/CHV already
stored a cached value there so just expand that to cover all platforms.

v2: Rebased to the latest
v3: Rebased to the latest
v4: Rebased to the latest
v5: Removed spurious call to 'intel_update_cdclk(dev)' based on
    Damien Lespiau's comment
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Mika Kahola <mika.kahola@intel.com>
Reviewed-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/intel_display.c

@@ -5747,7 +5747,7 @@ static int valleyview_get_vco(struct drm_i915_private *dev_priv)
 	return vco_freq[hpll_freq] * 1000;
 }
 
-static void vlv_update_cdclk(struct drm_device *dev)
+static void intel_update_cdclk(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 
@@ -5755,12 +5755,19 @@ static void vlv_update_cdclk(struct drm_device *dev)
 	DRM_DEBUG_DRIVER("Current CD clock rate: %d kHz\n",
 			 dev_priv->cdclk_freq);
 
+	/*
+	 * Program the gmbus_freq based on the cdclk frequency.
+	 * BSpec erroneously claims we should aim for 4MHz, but
+	 * in fact 1MHz is the correct frequency.
+	 */
+	if (IS_VALLEYVIEW(dev)) {
 		/*
 		 * Program the gmbus_freq based on the cdclk frequency.
 		 * BSpec erroneously claims we should aim for 4MHz, but
 		 * in fact 1MHz is the correct frequency.
 		 */
 		I915_WRITE(GMBUSFREQ_VLV, DIV_ROUND_UP(dev_priv->cdclk_freq, 1000));
+	}
 }
 
 /* Adjust CDclk dividers to allow high res or save power if possible */
@@ -5826,7 +5833,7 @@ static void valleyview_set_cdclk(struct drm_device *dev, int cdclk)
 
 	mutex_unlock(&dev_priv->sb_lock);
 
-	vlv_update_cdclk(dev);
+	intel_update_cdclk(dev);
 }
 
 static void cherryview_set_cdclk(struct drm_device *dev, int cdclk)
@@ -5867,7 +5874,7 @@ static void cherryview_set_cdclk(struct drm_device *dev, int cdclk)
 	}
 	mutex_unlock(&dev_priv->rps.hw_lock);
 
-	vlv_update_cdclk(dev);
+	intel_update_cdclk(dev);
 }
 
 static int valleyview_calc_cdclk(struct drm_i915_private *dev_priv,
@@ -9479,6 +9486,7 @@ static void hsw_restore_lcpll(struct drm_i915_private *dev_priv)
 	}
 
 	intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL);
+	intel_update_cdclk(dev_priv->dev);
 }
 
 /*
@@ -13273,6 +13281,8 @@ static void intel_shared_dpll_init(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 
+	intel_update_cdclk(dev);
+
 	if (HAS_DDI(dev))
 		intel_ddi_pll_init(dev);
 	else if (HAS_PCH_IBX(dev) || HAS_PCH_CPT(dev))
@@ -14848,13 +14858,9 @@ static void i915_disable_vga(struct drm_device *dev)
 
 void intel_modeset_init_hw(struct drm_device *dev)
 {
+	intel_update_cdclk(dev);
 	intel_prepare_ddi(dev);
-
-	if (IS_VALLEYVIEW(dev))
-		vlv_update_cdclk(dev);
-
 	intel_init_clock_gating(dev);
-
 	intel_enable_gt_powersave(dev);
 }