[PATCH 31/41] drm/bridge: analogix_dp: Move fast link training detect to set_bridge

[Sean Paul]

From: zain wang <wzz at rock-chips.com>

It's too early to detect fast link training, if other step after it failed,
we will set fast_link flag to 1, and retry set_bridge again. In this case
we will power down and power up panel power supply, and we will do fast link
training since we have set fast_link flag to 1. In fact, we should do full
link training now, not the fast link training. So we should move the fast
link detection at the end of set_bridge.

Cc: Tomasz Figa <tfiga at chromium.org>
Signed-off-by: zain wang <wzz at rock-chips.com>
Signed-off-by: Douglas Anderson <dianders at chromium.org>
Signed-off-by: Sean Paul <seanpaul at chromium.org>
---
 drivers/gpu/drm/bridge/analogix/analogix_dp_core.c | 42 +++++++++++++---------
 1 file changed, 26 insertions(+), 16 deletions(-)

diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
index 4ebbf3053639..65af5ef8ec12 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
+++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
@@ -599,7 +599,7 @@ static int analogix_dp_process_equalizer_training(struct analogix_dp_device *dp)
 {
 	int lane, lane_count, retval;
 	u32 reg;
-	u8 link_align, link_status[2], adjust_request[2], spread;
+	u8 link_align, link_status[2], adjust_request[2];
 
 	usleep_range(400, 401);
 
@@ -643,20 +643,6 @@ static int analogix_dp_process_equalizer_training(struct analogix_dp_device *dp)
 		dev_dbg(dp->dev, "final lane count = %.2x\n",
 			dp->link_train.lane_count);
 
-		retval = drm_dp_dpcd_readb(&dp->aux, DP_MAX_DOWNSPREAD,
-					   &spread);
-		if (retval != 1) {
-			dev_err(dp->dev, "failed to read downspread %d\n",
-				retval);
-			dp->fast_train_enable = false;
-		} else {
-			dp->fast_train_enable =
-				(spread & DP_NO_AUX_HANDSHAKE_LINK_TRAINING) ?
-					true : false;
-		}
-		dev_dbg(dp->dev, "fast link training %s\n",
-			dp->fast_train_enable ? "supported" : "unsupported");
-
 		dp->link_train.lt_state = FINISHED;
 
 		return 0;
@@ -994,6 +980,22 @@ static irqreturn_t analogix_dp_irq_thread(int irq, void *arg)
 	return IRQ_HANDLED;
 }
 
+static int analogix_dp_fast_link_train_detection(struct analogix_dp_device *dp)
+{
+	int ret;
+	u8 spread;
+
+	ret = drm_dp_dpcd_readb(&dp->aux, DP_MAX_DOWNSPREAD, &spread);
+	if (ret != 1) {
+		dev_err(dp->dev, "failed to read downspread %d\n", ret);
+		return ret;
+	}
+	dp->fast_train_enable = !!(spread & DP_NO_AUX_HANDSHAKE_LINK_TRAINING);
+	dev_dbg(dp->dev, "fast link training %s\n",
+		dp->fast_train_enable ? "supported" : "unsupported");
+	return 0;
+}
+
 static int analogix_dp_commit(struct analogix_dp_device *dp)
 {
 	int ret;
@@ -1036,8 +1038,16 @@ static int analogix_dp_commit(struct analogix_dp_device *dp)
 	if (ret)
 		return ret;
 
-	if (dp->psr_enable)
+	if (dp->psr_enable) {
 		ret = analogix_dp_enable_sink_psr(dp);
+		if (ret)
+			return ret;
+	}
+
+	/* Check whether panel supports fast training */
+	ret =  analogix_dp_fast_link_train_detection(dp);
+	if (ret)
+		dp->psr_enable = false;
 
 	return ret;
 }
-- 
2.12.0.246.ga2ecc84866-goog