drv/i915: Pull display_clock_mode out of VBT table

This tells the driver whether a CK505 clock source is available on
pre-PCH hardware. If so, it should be used as the non-SSC source,
leaving the internal clock for use as the SSC source.
Signed-off-by: Keith Packard <keithp@keithp.com>
Reviewed-by: Chris Wison <chris@chris-wilson.co.uk>

drivers/gpu/drm/i915/i915_drv.h

@@ -357,6 +357,7 @@ typedef struct drm_i915_private {
 	unsigned int lvds_vbt:1;
 	unsigned int int_crt_support:1;
 	unsigned int lvds_use_ssc:1;
+	unsigned int display_clock_mode:1;
 	int lvds_ssc_freq;
 	struct {
 		int rate;

drivers/gpu/drm/i915/intel_bios.c

@@ -309,11 +309,13 @@ parse_general_features(struct drm_i915_private *dev_priv,
 		dev_priv->lvds_use_ssc = general->enable_ssc;
 		dev_priv->lvds_ssc_freq =
 			intel_bios_ssc_frequency(dev, general->ssc_freq);
-		DRM_DEBUG_KMS("BDB_GENERAL_FEATURES int_tv_support %d int_crt_support %d lvds_use_ssc %d lvds_ssc_freq %d\n",
+		dev_priv->display_clock_mode = general->display_clock_mode;
+		DRM_DEBUG_KMS("BDB_GENERAL_FEATURES int_tv_support %d int_crt_support %d lvds_use_ssc %d lvds_ssc_freq %d display_clock_mode %d\n",
 			      dev_priv->int_tv_support,
 			      dev_priv->int_crt_support,
 			      dev_priv->lvds_use_ssc,
-			      dev_priv->lvds_ssc_freq);
+			      dev_priv->lvds_ssc_freq,
+			      dev_priv->display_clock_mode);
 	}
 }
 

drivers/gpu/drm/i915/intel_bios.h

@@ -120,7 +120,9 @@ struct bdb_general_features {
 	u8 ssc_freq:1;
 	u8 enable_lfp_on_override:1;
 	u8 disable_ssc_ddt:1;
-	u8 rsvd8:3; /* finish byte */
+	u8 rsvd7:1;
+	u8 display_clock_mode:1;
+	u8 rsvd8:1; /* finish byte */
 
         /* bits 3 */
 	u8 disable_smooth_vision:1;