drm/i915: Parse max HDMI TMDS clock from VBT

Starting from version 204 VBT can specify the max TMDS clock we are
allowed to use with HDMI ports. Parse that information and take it
into account when filtering modes and computing a crtc state.

Also take the opportunity to sort the platform check if ladder
from new to old.

v2: Add defines for the values into intel_vbt_defs.h (Jani)
    Don't fall back to 0 silently for unknown values (Jani)
    Skip the debug print for the 0 case (Jani)

Cc: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171030145702.23662-1-ville.syrjala@linux.intel.com

drivers/gpu/drm/i915/i915_drv.h

@@ -1698,6 +1698,8 @@ enum modeset_restore {
 #define DDC_PIN_D  0x06
 
 struct ddi_vbt_port_info {
+	int max_tmds_clock;
+
 	/*
 	 * This is an index in the HDMI/DVI DDI buffer translation table.
 	 * The special value HDMI_LEVEL_SHIFT_UNKNOWN means the VBT didn't

drivers/gpu/drm/i915/intel_bios.c

@@ -1227,6 +1227,30 @@ static void parse_ddi_port(struct drm_i915_private *dev_priv, enum port port,
 		info->hdmi_level_shift = hdmi_level_shift;
 	}
 
+	if (bdb_version >= 204) {
+		int max_tmds_clock;
+
+		switch (child->hdmi_max_data_rate) {
+		default:
+			MISSING_CASE(child->hdmi_max_data_rate);
+			/* fall through */
+		case HDMI_MAX_DATA_RATE_PLATFORM:
+			max_tmds_clock = 0;
+			break;
+		case HDMI_MAX_DATA_RATE_297:
+			max_tmds_clock = 297000;
+			break;
+		case HDMI_MAX_DATA_RATE_165:
+			max_tmds_clock = 165000;
+			break;
+		}
+
+		if (max_tmds_clock)
+			DRM_DEBUG_KMS("VBT HDMI max TMDS clock for port %c: %d kHz\n",
+				      port_name(port), max_tmds_clock);
+		info->max_tmds_clock = max_tmds_clock;
+	}
+
 	/* Parse the I_boost config for SKL and above */
 	if (bdb_version >= 196 && child->iboost) {
 		info->dp_boost_level = translate_iboost(child->dp_iboost_level);

drivers/gpu/drm/i915/intel_hdmi.c

@@ -1224,24 +1224,34 @@ static void pch_post_disable_hdmi(struct intel_encoder *encoder,
 	intel_disable_hdmi(encoder, old_crtc_state, old_conn_state);
 }
 
-static int intel_hdmi_source_max_tmds_clock(struct drm_i915_private *dev_priv)
+static int intel_hdmi_source_max_tmds_clock(struct intel_encoder *encoder)
 {
-	if (IS_G4X(dev_priv))
-		return 165000;
-	else if (IS_GEMINILAKE(dev_priv))
-		return 594000;
-	else if (IS_HASWELL(dev_priv) || INTEL_INFO(dev_priv)->gen >= 8)
-		return 300000;
+	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
+	const struct ddi_vbt_port_info *info =
+		&dev_priv->vbt.ddi_port_info[encoder->port];
+	int max_tmds_clock;
+
+	if (IS_GEMINILAKE(dev_priv))
+		max_tmds_clock = 594000;
+	else if (INTEL_GEN(dev_priv) >= 8 || IS_HASWELL(dev_priv))
+		max_tmds_clock = 300000;
+	else if (INTEL_GEN(dev_priv) >= 5)
+		max_tmds_clock = 225000;
 	else
-		return 225000;
+		max_tmds_clock = 165000;
+
+	if (info->max_tmds_clock)
+		max_tmds_clock = min(max_tmds_clock, info->max_tmds_clock);
+
+	return max_tmds_clock;
 }
 
 static int hdmi_port_clock_limit(struct intel_hdmi *hdmi,
 				 bool respect_downstream_limits,
 				 bool force_dvi)
 {
-	struct drm_device *dev = intel_hdmi_to_dev(hdmi);
-	int max_tmds_clock = intel_hdmi_source_max_tmds_clock(to_i915(dev));
+	struct intel_encoder *encoder = &hdmi_to_dig_port(hdmi)->base;
+	int max_tmds_clock = intel_hdmi_source_max_tmds_clock(encoder);
 
 	if (respect_downstream_limits) {
 		struct intel_connector *connector = hdmi->attached_connector;

drivers/gpu/drm/i915/intel_vbt_defs.h

@@ -304,6 +304,10 @@ struct bdb_general_features {
 #define DVO_PORT_MIPIC		23				/* 171 */
 #define DVO_PORT_MIPID		24				/* 171 */
 
+#define HDMI_MAX_DATA_RATE_PLATFORM	0			/* 204 */
+#define HDMI_MAX_DATA_RATE_297		1			/* 204 */
+#define HDMI_MAX_DATA_RATE_165		2			/* 204 */
+
 #define LEGACY_CHILD_DEVICE_CONFIG_SIZE		33
 
 /* DDC Bus DDI Type 155+ */