drm/i915/dp: Move link train params to a substruct in intel_dp

For clarity move the link training parameters updated during link
training based on the pass/fail LT result under a substruct in intel_dp.
This prepares for later patches in this patchset adding similar params
here. Rename intel_dp_reset_max_link_params() to
intel_dp_reset_link_params() to better reflect what state gets reset.

v2: Add the parameters to a more generic link substruct. (Jani)

Cc: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240610164933.2947366-3-imre.deak@intel.com

drivers/gpu/drm/i915/display/intel_display_types.h

@@ -1739,7 +1739,6 @@ struct intel_dp {
 	u8 lane_count;
 	u8 sink_count;
 	bool link_trained;
-	bool reset_link_params;
 	bool use_max_params;
 	u8 dpcd[DP_RECEIVER_CAP_SIZE];
 	u8 psr_dpcd[EDP_PSR_RECEIVER_CAP_SIZE];
@@ -1761,10 +1760,14 @@ struct intel_dp {
 	/* intersection of source and sink rates */
 	int num_common_rates;
 	int common_rates[DP_MAX_SUPPORTED_RATES];
+	struct {
+		/* TODO: move the rest of link specific fields to here */
 		/* Max lane count for the current link */
-	int max_link_lane_count;
+		int max_lane_count;
 		/* Max rate for the current link */
-	int max_link_rate;
+		int max_rate;
+	} link;
+	bool reset_link_params;
 	int mso_link_count;
 	int mso_pixel_overlap;
 	/* sink or branch descriptor */

drivers/gpu/drm/i915/display/intel_dp.c

@@ -373,13 +373,13 @@ int intel_dp_max_common_lane_count(struct intel_dp *intel_dp)
 
 int intel_dp_max_lane_count(struct intel_dp *intel_dp)
 {
-	switch (intel_dp->max_link_lane_count) {
+	switch (intel_dp->link.max_lane_count) {
 	case 1:
 	case 2:
 	case 4:
-		return intel_dp->max_link_lane_count;
+		return intel_dp->link.max_lane_count;
 	default:
-		MISSING_CASE(intel_dp->max_link_lane_count);
+		MISSING_CASE(intel_dp->link.max_lane_count);
 		return 1;
 	}
 }
@@ -645,7 +645,7 @@ static bool intel_dp_link_params_valid(struct intel_dp *intel_dp, int link_rate,
 	 * boot-up.
 	 */
 	if (link_rate == 0 ||
-	    link_rate > intel_dp->max_link_rate)
+	    link_rate > intel_dp->link.max_rate)
 		return false;
 
 	if (lane_count == 0 ||
@@ -706,8 +706,8 @@ int intel_dp_get_link_train_fallback_values(struct intel_dp *intel_dp,
 				    "Retrying Link training for eDP with same parameters\n");
 			return 0;
 		}
-		intel_dp->max_link_rate = intel_dp_common_rate(intel_dp, index - 1);
-		intel_dp->max_link_lane_count = lane_count;
+		intel_dp->link.max_rate = intel_dp_common_rate(intel_dp, index - 1);
+		intel_dp->link.max_lane_count = lane_count;
 	} else if (lane_count > 1) {
 		if (intel_dp_is_edp(intel_dp) &&
 		    !intel_dp_can_link_train_fallback_for_edp(intel_dp,
@@ -717,8 +717,8 @@ int intel_dp_get_link_train_fallback_values(struct intel_dp *intel_dp,
 				    "Retrying Link training for eDP with same parameters\n");
 			return 0;
 		}
-		intel_dp->max_link_rate = intel_dp_max_common_rate(intel_dp);
-		intel_dp->max_link_lane_count = lane_count >> 1;
+		intel_dp->link.max_rate = intel_dp_max_common_rate(intel_dp);
+		intel_dp->link.max_lane_count = lane_count >> 1;
 	} else {
 		drm_err(&i915->drm, "Link Training Unsuccessful\n");
 		return -1;
@@ -1383,7 +1383,7 @@ intel_dp_max_link_rate(struct intel_dp *intel_dp)
 {
 	int len;
 
-	len = intel_dp_common_len_rate_limit(intel_dp, intel_dp->max_link_rate);
+	len = intel_dp_common_len_rate_limit(intel_dp, intel_dp->link.max_rate);
 
 	return intel_dp_common_rate(intel_dp, len - 1);
 }
@@ -3027,10 +3027,10 @@ void intel_dp_set_link_params(struct intel_dp *intel_dp,
 	intel_dp->lane_count = lane_count;
 }
 
-static void intel_dp_reset_max_link_params(struct intel_dp *intel_dp)
+static void intel_dp_reset_link_params(struct intel_dp *intel_dp)
 {
-	intel_dp->max_link_lane_count = intel_dp_max_common_lane_count(intel_dp);
-	intel_dp->max_link_rate = intel_dp_max_common_rate(intel_dp);
+	intel_dp->link.max_lane_count = intel_dp_max_common_lane_count(intel_dp);
+	intel_dp->link.max_rate = intel_dp_max_common_rate(intel_dp);
 }
 
 /* Enable backlight PWM and backlight PP control. */
@@ -3365,7 +3365,7 @@ void intel_dp_sync_state(struct intel_encoder *encoder,
 	intel_dp_tunnel_resume(intel_dp, crtc_state, dpcd_updated);
 
 	if (crtc_state)
-		intel_dp_reset_max_link_params(intel_dp);
+		intel_dp_reset_link_params(intel_dp);
 }
 
 bool intel_dp_initial_fastset_check(struct intel_encoder *encoder,
@@ -5907,7 +5907,7 @@ intel_dp_detect(struct drm_connector *connector,
 	 * supports link training fallback params.
 	 */
 	if (intel_dp->reset_link_params || intel_dp->is_mst) {
-		intel_dp_reset_max_link_params(intel_dp);
+		intel_dp_reset_link_params(intel_dp);
 		intel_dp->reset_link_params = false;
 	}
 
@@ -6761,7 +6761,7 @@ intel_dp_init_connector(struct intel_digital_port *dig_port,
 
 	intel_dp_set_source_rates(intel_dp);
 	intel_dp_set_common_rates(intel_dp);
-	intel_dp_reset_max_link_params(intel_dp);
+	intel_dp_reset_link_params(intel_dp);
 
 	/* init MST on ports that can support it */
 	intel_dp_mst_encoder_init(dig_port,