video: exynos_dp: Clean up SW link training

Clean up some of the SW training code to make it more clear and reduce
duplicate code.

[jg1.han@samsung.com: used exynos_dp_write_bytes_to_dpcd()]
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Jingoo Han <jg1.han@samsung.com>

drivers/video/exynos/exynos_dp_core.c

@@ -277,7 +277,7 @@ static int exynos_dp_link_start(struct exynos_dp_device *dp)
 
 	/* Set sink to D0 (Sink Not Ready) mode. */
 	retval = exynos_dp_write_byte_to_dpcd(dp, DPCD_ADDR_SINK_POWER_STATE,
-				DPCD_SET_POWER_STATE_D0);
+			DPCD_SET_POWER_STATE_D0);
 	if (retval)
 		return retval;
 
@@ -302,17 +302,18 @@ static int exynos_dp_link_start(struct exynos_dp_device *dp)
 	exynos_dp_set_training_pattern(dp, TRAINING_PTN1);
 
 	/* Set RX training pattern */
-	exynos_dp_write_byte_to_dpcd(dp,
-		DPCD_ADDR_TRAINING_PATTERN_SET,
-		DPCD_SCRAMBLING_DISABLED |
-		DPCD_TRAINING_PATTERN_1);
+	retval = exynos_dp_write_byte_to_dpcd(dp,
+			DPCD_ADDR_TRAINING_PATTERN_SET,
+			DPCD_SCRAMBLING_DISABLED | DPCD_TRAINING_PATTERN_1);
+	if (retval)
+		return retval;
 
 	for (lane = 0; lane < lane_count; lane++)
 		buf[lane] = DPCD_PRE_EMPHASIS_PATTERN2_LEVEL0 |
 			    DPCD_VOLTAGE_SWING_PATTERN1_LEVEL0;
-	retval = exynos_dp_write_bytes_to_dpcd(dp,
-		DPCD_ADDR_TRAINING_LANE0_SET,
-		lane_count, buf);
+
+	retval = exynos_dp_write_bytes_to_dpcd(dp, DPCD_ADDR_TRAINING_LANE0_SET,
+			lane_count, buf);
 
 	return retval;
 }
@@ -338,18 +339,17 @@ static int exynos_dp_clock_recovery_ok(u8 link_status[2], int lane_count)
 	return 0;
 }
 
-static int exynos_dp_channel_eq_ok(u8 link_align[3], int lane_count)
+static int exynos_dp_channel_eq_ok(u8 link_status[2], u8 link_align,
+				int lane_count)
 {
 	int lane;
-	u8 lane_align;
 	u8 lane_status;
 
-	lane_align = link_align[2];
-	if ((lane_align & DPCD_INTERLANE_ALIGN_DONE) == 0)
+	if ((link_align & DPCD_INTERLANE_ALIGN_DONE) == 0)
 		return -EINVAL;
 
 	for (lane = 0; lane < lane_count; lane++) {
-		lane_status = exynos_dp_get_lane_status(link_align, lane);
+		lane_status = exynos_dp_get_lane_status(link_status, lane);
 		lane_status &= DPCD_CHANNEL_EQ_BITS;
 		if (lane_status != DPCD_CHANNEL_EQ_BITS)
 			return -EINVAL;
@@ -433,22 +433,47 @@ static void exynos_dp_reduce_link_rate(struct exynos_dp_device *dp)
 	dp->link_train.lt_state = FAILED;
 }
 
+static void exynos_dp_get_adjust_training_lane(struct exynos_dp_device *dp,
+					u8 adjust_request[2])
+{
+	int lane, lane_count;
+	u8 voltage_swing, pre_emphasis, training_lane;
+
+	lane_count = dp->link_train.lane_count;
+	for (lane = 0; lane < lane_count; lane++) {
+		voltage_swing = exynos_dp_get_adjust_request_voltage(
+						adjust_request, lane);
+		pre_emphasis = exynos_dp_get_adjust_request_pre_emphasis(
+						adjust_request, lane);
+		training_lane = DPCD_VOLTAGE_SWING_SET(voltage_swing) |
+				DPCD_PRE_EMPHASIS_SET(pre_emphasis);
+
+		if (voltage_swing == VOLTAGE_LEVEL_3)
+			training_lane |= DPCD_MAX_SWING_REACHED;
+		if (pre_emphasis == PRE_EMPHASIS_LEVEL_3)
+			training_lane |= DPCD_MAX_PRE_EMPHASIS_REACHED;
+
+		dp->link_train.training_lane[lane] = training_lane;
+	}
+}
+
 static int exynos_dp_process_clock_recovery(struct exynos_dp_device *dp)
 {
-	u8 link_status[2];
 	int lane, lane_count, retval;
-
-	u8 adjust_request[2];
-	u8 voltage_swing;
-	u8 pre_emphasis;
-	u8 training_lane;
+	u8 voltage_swing, pre_emphasis, training_lane;
+	u8 link_status[2], adjust_request[2];
 
 	usleep_range(100, 101);
 
 	lane_count = dp->link_train.lane_count;
 
-	retval =  exynos_dp_read_bytes_from_dpcd(dp, DPCD_ADDR_LANE0_1_STATUS,
-				2, link_status);
+	retval =  exynos_dp_read_bytes_from_dpcd(dp,
+			DPCD_ADDR_LANE0_1_STATUS, 2, link_status);
+	if (retval)
+		return retval;
+
+	retval =  exynos_dp_read_bytes_from_dpcd(dp,
+			DPCD_ADDR_ADJUST_REQUEST_LANE0_1, 2, adjust_request);
 	if (retval)
 		return retval;
 
@@ -456,43 +481,10 @@ static int exynos_dp_process_clock_recovery(struct exynos_dp_device *dp)
 		/* set training pattern 2 for EQ */
 		exynos_dp_set_training_pattern(dp, TRAINING_PTN2);
 
-		for (lane = 0; lane < lane_count; lane++) {
-			retval = exynos_dp_read_bytes_from_dpcd(dp,
-					DPCD_ADDR_ADJUST_REQUEST_LANE0_1,
-					2, adjust_request);
-			if (retval)
-				return retval;
-
-			voltage_swing = exynos_dp_get_adjust_request_voltage(
-							adjust_request, lane);
-			pre_emphasis = exynos_dp_get_adjust_request_pre_emphasis(
-							adjust_request, lane);
-			training_lane = DPCD_VOLTAGE_SWING_SET(voltage_swing) |
-					DPCD_PRE_EMPHASIS_SET(pre_emphasis);
-
-			if (voltage_swing == VOLTAGE_LEVEL_3)
-				training_lane |= DPCD_MAX_SWING_REACHED;
-			if (pre_emphasis == PRE_EMPHASIS_LEVEL_3)
-				training_lane |= DPCD_MAX_PRE_EMPHASIS_REACHED;
-
-			dp->link_train.training_lane[lane] = training_lane;
-
-			exynos_dp_set_lane_link_training(dp,
-				dp->link_train.training_lane[lane],
-				lane);
-		}
-
 		retval = exynos_dp_write_byte_to_dpcd(dp,
-			DPCD_ADDR_TRAINING_PATTERN_SET,
-			DPCD_SCRAMBLING_DISABLED |
-			DPCD_TRAINING_PATTERN_2);
-		if (retval)
-			return retval;
-
-		retval = exynos_dp_write_bytes_to_dpcd(dp,
-			DPCD_ADDR_TRAINING_LANE0_SET,
-			lane_count,
-			dp->link_train.training_lane);
+				DPCD_ADDR_TRAINING_PATTERN_SET,
+				DPCD_SCRAMBLING_DISABLED |
+				DPCD_TRAINING_PATTERN_2);
 		if (retval)
 			return retval;
 
@@ -502,162 +494,116 @@ static int exynos_dp_process_clock_recovery(struct exynos_dp_device *dp)
 		for (lane = 0; lane < lane_count; lane++) {
 			training_lane = exynos_dp_get_lane_link_training(
 							dp, lane);
-			retval = exynos_dp_read_bytes_from_dpcd(dp,
-					DPCD_ADDR_ADJUST_REQUEST_LANE0_1,
-					2, adjust_request);
-			if (retval)
-				return retval;
-
 			voltage_swing = exynos_dp_get_adjust_request_voltage(
 							adjust_request, lane);
 			pre_emphasis = exynos_dp_get_adjust_request_pre_emphasis(
 							adjust_request, lane);
 
-			if (voltage_swing == VOLTAGE_LEVEL_3 ||
-			    pre_emphasis == PRE_EMPHASIS_LEVEL_3) {
-				dev_err(dp->dev, "voltage or pre emphasis reached max level\n");
-				goto reduce_link_rate;
-			}
-
-			if ((DPCD_VOLTAGE_SWING_GET(training_lane) ==
-					voltage_swing) &&
-			   (DPCD_PRE_EMPHASIS_GET(training_lane) ==
-					pre_emphasis)) {
+			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) {
-					dev_err(dp->dev, "CR Max loop\n");
-					goto reduce_link_rate;
-				}
-			}
-
-			training_lane = DPCD_VOLTAGE_SWING_SET(voltage_swing) |
-					DPCD_PRE_EMPHASIS_SET(pre_emphasis);
 
-			if (voltage_swing == VOLTAGE_LEVEL_3)
-				training_lane |= DPCD_MAX_SWING_REACHED;
-			if (pre_emphasis == PRE_EMPHASIS_LEVEL_3)
-				training_lane |= DPCD_MAX_PRE_EMPHASIS_REACHED;
+			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);
+				exynos_dp_reduce_link_rate(dp);
+				return -EIO;
+			}
+		}
+	}
 
-			dp->link_train.training_lane[lane] = training_lane;
+	exynos_dp_get_adjust_training_lane(dp, adjust_request);
 
-			exynos_dp_set_lane_link_training(dp,
-				dp->link_train.training_lane[lane], lane);
-		}
+	for (lane = 0; lane < lane_count; lane++)
+		exynos_dp_set_lane_link_training(dp,
+			dp->link_train.training_lane[lane], lane);
 
-		retval = exynos_dp_write_bytes_to_dpcd(dp,
-				DPCD_ADDR_TRAINING_LANE0_SET, lane_count,
-				dp->link_train.training_lane);
-		if (retval)
-			return retval;
-	}
+	retval = exynos_dp_write_bytes_to_dpcd(dp,
+			DPCD_ADDR_TRAINING_LANE0_SET, lane_count,
+			dp->link_train.training_lane);
+	if (retval)
+		return retval;
 
 	return retval;
-
-reduce_link_rate:
-	exynos_dp_reduce_link_rate(dp);
-	return -EIO;
 }
 
 static int exynos_dp_process_equalizer_training(struct exynos_dp_device *dp)
 {
-	u8 link_status[2];
-	u8 link_align[3];
 	int lane, lane_count, retval;
 	u32 reg;
-
-	u8 adjust_request[2];
-	u8 voltage_swing;
-	u8 pre_emphasis;
-	u8 training_lane;
+	u8 link_align, link_status[2], adjust_request[2];
 
 	usleep_range(400, 401);
 
 	lane_count = dp->link_train.lane_count;
 
-	retval = exynos_dp_read_bytes_from_dpcd(dp, DPCD_ADDR_LANE0_1_STATUS,
-				2, link_status);
+	retval = exynos_dp_read_bytes_from_dpcd(dp,
+			DPCD_ADDR_LANE0_1_STATUS, 2, link_status);
 	if (retval)
 		return retval;
 
-	if (exynos_dp_clock_recovery_ok(link_status, lane_count) == 0) {
-		link_align[0] = link_status[0];
-		link_align[1] = link_status[1];
-
-		exynos_dp_read_byte_from_dpcd(dp,
-			DPCD_ADDR_LANE_ALIGN_STATUS_UPDATED,
-			&link_align[2]);
-
-		for (lane = 0; lane < lane_count; lane++) {
-			retval = exynos_dp_read_bytes_from_dpcd(dp,
-					DPCD_ADDR_ADJUST_REQUEST_LANE0_1,
-					2, adjust_request);
-			if (retval)
-				return retval;
+	if (exynos_dp_clock_recovery_ok(link_status, lane_count)) {
+		exynos_dp_reduce_link_rate(dp);
+		return -EIO;
+	}
 
-			voltage_swing = exynos_dp_get_adjust_request_voltage(
-							adjust_request, lane);
-			pre_emphasis = exynos_dp_get_adjust_request_pre_emphasis(
-							adjust_request, lane);
-			training_lane = DPCD_VOLTAGE_SWING_SET(voltage_swing) |
-					DPCD_PRE_EMPHASIS_SET(pre_emphasis);
+	retval = exynos_dp_read_bytes_from_dpcd(dp,
+			DPCD_ADDR_ADJUST_REQUEST_LANE0_1, 2, adjust_request);
+	if (retval)
+		return retval;
 
-			if (voltage_swing == VOLTAGE_LEVEL_3)
-				training_lane |= DPCD_MAX_SWING_REACHED;
-			if (pre_emphasis == PRE_EMPHASIS_LEVEL_3)
-				training_lane |= DPCD_MAX_PRE_EMPHASIS_REACHED;
+	retval = exynos_dp_read_byte_from_dpcd(dp,
+			DPCD_ADDR_LANE_ALIGN_STATUS_UPDATED, &link_align);
+	if (retval)
+		return retval;
 
-			dp->link_train.training_lane[lane] = training_lane;
-		}
+	exynos_dp_get_adjust_training_lane(dp, adjust_request);
 
-		if (exynos_dp_channel_eq_ok(link_align, lane_count) == 0) {
-			/* traing pattern Set to Normal */
-			exynos_dp_training_pattern_dis(dp);
+	if (!exynos_dp_channel_eq_ok(link_status, link_align, lane_count)) {
+		/* traing pattern Set to Normal */
+		exynos_dp_training_pattern_dis(dp);
 
-			dev_info(dp->dev, "Link Training success!\n");
+		dev_info(dp->dev, "Link Training success!\n");
 
-			exynos_dp_get_link_bandwidth(dp, &reg);
-			dp->link_train.link_rate = reg;
-			dev_dbg(dp->dev, "final bandwidth = %.2x\n",
-				dp->link_train.link_rate);
+		exynos_dp_get_link_bandwidth(dp, &reg);
+		dp->link_train.link_rate = reg;
+		dev_dbg(dp->dev, "final bandwidth = %.2x\n",
+			dp->link_train.link_rate);
 
-			exynos_dp_get_lane_count(dp, &reg);
-			dp->link_train.lane_count = reg;
-			dev_dbg(dp->dev, "final lane count = %.2x\n",
-				dp->link_train.lane_count);
+		exynos_dp_get_lane_count(dp, &reg);
+		dp->link_train.lane_count = reg;
+		dev_dbg(dp->dev, "final lane count = %.2x\n",
+			dp->link_train.lane_count);
 
-			/* set enhanced mode if available */
-			exynos_dp_set_enhanced_mode(dp);
-			dp->link_train.lt_state = FINISHED;
-		} else {
-			/* not all locked */
-			dp->link_train.eq_loop++;
+		/* set enhanced mode if available */
+		exynos_dp_set_enhanced_mode(dp);
+		dp->link_train.lt_state = FINISHED;
 
-			if (dp->link_train.eq_loop > MAX_EQ_LOOP) {
-				dev_err(dp->dev, "EQ Max loop\n");
-				goto reduce_link_rate;
-			}
+		return 0;
+	}
 
-			for (lane = 0; lane < lane_count; lane++)
-				exynos_dp_set_lane_link_training(dp,
-					dp->link_train.training_lane[lane],
-					lane);
+	/* not all locked */
+	dp->link_train.eq_loop++;
 
-			retval = exynos_dp_write_bytes_to_dpcd(dp,
-					DPCD_ADDR_TRAINING_LANE0_SET,
-					lane_count,
-					dp->link_train.training_lane);
-			if (retval)
-				return retval;
-		}
-	} else {
-		goto reduce_link_rate;
+	if (dp->link_train.eq_loop > MAX_EQ_LOOP) {
+		dev_err(dp->dev, "EQ Max loop\n");
+		exynos_dp_reduce_link_rate(dp);
+		return -EIO;
 	}
 
-	return 0;
+	for (lane = 0; lane < lane_count; lane++)
+		exynos_dp_set_lane_link_training(dp,
+			dp->link_train.training_lane[lane], lane);
 
-reduce_link_rate:
-	exynos_dp_reduce_link_rate(dp);
-	return -EIO;
+	retval = exynos_dp_write_bytes_to_dpcd(dp, DPCD_ADDR_TRAINING_LANE0_SET,
+			lane_count, dp->link_train.training_lane);
+
+	return retval;
 }
 
 static void exynos_dp_get_max_rx_bandwidth(struct exynos_dp_device *dp,