drm/i915: Handle 320 vs. 333 MHz cdclk on vlv

Depending on the HPLL frequency one of the supported cdclk frquencies is
either 320MHz or 333MHz. Figure out which one it is to accurately pick
the minimal required cdclk. This would also avoid a warning from the
cdclk code where it compares the actual cdclk read out from the hardware
with a value that was calculated using valleyview_calc_cdclk().

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_display.c

@@ -4545,19 +4545,22 @@ static void valleyview_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;
+
 	/*
 	 * Really only a few cases to deal with, as only 4 CDclks are supported:
 	 *   200MHz
 	 *   267MHz
-	 *   320MHz
+	 *   320/333MHz (depends on HPLL freq)
 	 *   400MHz
 	 * So we check to see whether we're above 90% of the lower bin and
 	 * adjust if needed.
 	 */
-	if (max_pixclk > 320000*9/10)
+	if (max_pixclk > freq_320*9/10)
 		return 400000;
 	else if (max_pixclk > 266667*9/10)
-		return 320000;
+		return freq_320;
 	else
 		return 266667;
 	/* Looks like the 200MHz CDclk freq doesn't work on some configs */