drm/bridge: analogix_dp: don't adjust further when clock recovery succeeded

Take a early return from the clock recovery training when the sink reports
CR_DONE for all lanes. There is no point in trying to adjust the link
parameters further.
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Reviewed-by: Robert Foss <rfoss@kernel.org>
Signed-off-by: Robert Foss <rfoss@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240318203925.2837689-3-l.stach@pengutronix.de

drivers/gpu/drm/bridge/analogix/analogix_dp_core.c

@@ -410,11 +410,6 @@ static int analogix_dp_process_clock_recovery(struct analogix_dp_device *dp)
 	if (retval < 0)
 		return retval;
 
-	retval = drm_dp_dpcd_read(&dp->aux, DP_ADJUST_REQUEST_LANE0_1,
-				  adjust_request, 2);
-	if (retval < 0)
-		return retval;
-
 	if (analogix_dp_clock_recovery_ok(link_status, lane_count) == 0) {
 		/* set training pattern 2 for EQ */
 		analogix_dp_set_training_pattern(dp, TRAINING_PTN2);
@@ -427,30 +422,32 @@ static int analogix_dp_process_clock_recovery(struct analogix_dp_device *dp)
 
 		dev_dbg(dp->dev, "Link Training Clock Recovery success\n");
 		dp->link_train.lt_state = EQUALIZER_TRAINING;
-	} else {
-		for (lane = 0; lane < lane_count; lane++) {
-			training_lane = analogix_dp_get_lane_link_training(
-							dp, lane);
-			voltage_swing = analogix_dp_get_adjust_request_voltage(
-							adjust_request, lane);
-			pre_emphasis = analogix_dp_get_adjust_request_pre_emphasis(
-							adjust_request, lane);
-
-			if (DPCD_VOLTAGE_SWING_GET(training_lane) ==
-					voltage_swing &&
-			    DPCD_PRE_EMPHASIS_GET(training_lane) ==
-					pre_emphasis)
-				dp->link_train.cr_loop[lane]++;
-
-			if (dp->link_train.cr_loop[lane] == MAX_CR_LOOP ||
-			    voltage_swing == VOLTAGE_LEVEL_3 ||
-			    pre_emphasis == PRE_EMPHASIS_LEVEL_3) {
-				dev_err(dp->dev, "CR Max reached (%d,%d,%d)\n",
-					dp->link_train.cr_loop[lane],
-					voltage_swing, pre_emphasis);
-				analogix_dp_reduce_link_rate(dp);
-				return -EIO;
-			}
+
+		return 0;
+	}
+
+	retval = drm_dp_dpcd_read(&dp->aux, DP_ADJUST_REQUEST_LANE0_1,
+				  adjust_request, 2);
+	if (retval < 0)
+		return retval;
+
+	for (lane = 0; lane < lane_count; lane++) {
+		training_lane = analogix_dp_get_lane_link_training(dp, lane);
+		voltage_swing = analogix_dp_get_adjust_request_voltage(adjust_request, lane);
+		pre_emphasis = analogix_dp_get_adjust_request_pre_emphasis(adjust_request, lane);
+
+		if (DPCD_VOLTAGE_SWING_GET(training_lane) == voltage_swing &&
+		    DPCD_PRE_EMPHASIS_GET(training_lane) == pre_emphasis)
+			dp->link_train.cr_loop[lane]++;
+
+		if (dp->link_train.cr_loop[lane] == MAX_CR_LOOP ||
+		    voltage_swing == VOLTAGE_LEVEL_3 ||
+		    pre_emphasis == PRE_EMPHASIS_LEVEL_3) {
+			dev_err(dp->dev, "CR Max reached (%d,%d,%d)\n",
+				dp->link_train.cr_loop[lane],
+				voltage_swing, pre_emphasis);
+			analogix_dp_reduce_link_rate(dp);
+			return -EIO;
 		}
 	}