drm/i915: Cache HPLL frequency on VLV/CHV

We need the HPLL frequency when calculating cdclk. Currently we read
that out from the hardware every single time, which isn't going to fly
very well if the device is runtime suspended. So cache the HPLL
frequency in dev_priv and use the cached value.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reference: https://bugs.freedesktop.org/show_bug.cgi?id=82939
Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.h

@@ -1613,6 +1613,7 @@ struct drm_i915_private {
 
 	unsigned int fsb_freq, mem_freq, is_ddr3;
 	unsigned int vlv_cdclk_freq;
+	unsigned int hpll_freq;
 
 	/**
 	 * wq - Driver workqueue for GEM.

drivers/gpu/drm/i915/intel_display.c

@@ -4756,10 +4756,9 @@ static void valleyview_set_cdclk(struct drm_device *dev, int cdclk)
 	mutex_unlock(&dev_priv->rps.hw_lock);
 
 	if (cdclk == 400000) {
-		u32 divider, vco;
+		u32 divider;
 
-		vco = valleyview_get_vco(dev_priv);
-		divider = DIV_ROUND_CLOSEST(vco << 1, cdclk) - 1;
+		divider = DIV_ROUND_CLOSEST(dev_priv->hpll_freq << 1, cdclk) - 1;
 
 		mutex_lock(&dev_priv->dpio_lock);
 		/* adjust cdclk divider */
@@ -4838,8 +4837,7 @@ static void cherryview_set_cdclk(struct drm_device *dev, int cdclk)
 static int valleyview_calc_cdclk(struct drm_i915_private *dev_priv,
 				 int max_pixclk)
 {
-	int vco = valleyview_get_vco(dev_priv);
-	int freq_320 = (vco <<  1) % 320000 != 0 ? 333333 : 320000;
+	int freq_320 = (dev_priv->hpll_freq <<  1) % 320000 != 0 ? 333333 : 320000;
 
 	/* FIXME: Punit isn't quite ready yet */
 	if (IS_CHERRYVIEW(dev_priv->dev))
@@ -5544,7 +5542,6 @@ static int intel_crtc_compute_config(struct intel_crtc *crtc,
 static int valleyview_get_display_clock_speed(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
-	int vco = valleyview_get_vco(dev_priv);
 	u32 val;
 	int divider;
 
@@ -5552,6 +5549,9 @@ static int valleyview_get_display_clock_speed(struct drm_device *dev)
 	if (IS_CHERRYVIEW(dev))
 		return 400000;
 
+	if (dev_priv->hpll_freq == 0)
+		dev_priv->hpll_freq = valleyview_get_vco(dev_priv);
+
 	mutex_lock(&dev_priv->dpio_lock);
 	val = vlv_cck_read(dev_priv, CCK_DISPLAY_CLOCK_CONTROL);
 	mutex_unlock(&dev_priv->dpio_lock);
@@ -5562,7 +5562,7 @@ static int valleyview_get_display_clock_speed(struct drm_device *dev)
 	     (divider << DISPLAY_FREQUENCY_STATUS_SHIFT),
 	     "cdclk change in progress\n");
 
-	return DIV_ROUND_CLOSEST(vco << 1, divider + 1);
+	return DIV_ROUND_CLOSEST(dev_priv->hpll_freq << 1, divider + 1);
 }
 
 static int i945_get_display_clock_speed(struct drm_device *dev)