linux-kernel - [PATCH 2/3] drm/bridge: it6505: modify DP link training work

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Message-Id: <20250124-fix-link-training-v1-2-09511050bb2c@ite.com.tw>
Date: Fri, 24 Jan 2025 10:29:51 +0800
From: Hermes Wu via B4 Relay <devnull+Hermes.wu.ite.com.tw@...nel.org>
To: Andrzej Hajda <andrzej.hajda@...el.com>, 
 Neil Armstrong <neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>, 
 Laurent Pinchart <Laurent.pinchart@...asonboard.com>, 
 Jonas Karlman <jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>, 
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>
Cc: Pet.Weng@....com.tw, Kenneth.Hung@....com.tw, treapking@...omium.org, 
 dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org, 
 Hermes Wu <Hermes.wu@....com.tw>
Subject: [PATCH 2/3] drm/bridge: it6505: modify DP link training work

From: Hermes Wu <Hermes.wu@....com.tw>

The DP link training work include auto training and after
auto training failed "auto_train_retry" times, it switch to
step training mode.

It will more efficiency that finish link auto training,
include retry, and step training in a work, rather than
re-schedule train work when each training fail.

it6505_dump() is remove from link trainig work, it takes too much
time to read all register area, and is not necessary.

Signed-off-by: Hermes Wu <Hermes.wu@....com.tw>
---
 drivers/gpu/drm/bridge/ite-it6505.c | 35 ++++++++++++++++-------------------
 1 file changed, 16 insertions(+), 19 deletions(-)

diff --git a/drivers/gpu/drm/bridge/ite-it6505.c b/drivers/gpu/drm/bridge/ite-it6505.c
index dc1179c8338e27866f6adda4ef8fb2950336221b..11231a642bbe185c4f36bf5f2a0b115fa056213b 100644
--- a/drivers/gpu/drm/bridge/ite-it6505.c
+++ b/drivers/gpu/drm/bridge/ite-it6505.c
@@ -666,7 +666,7 @@ static int it6505_get_dpcd(struct it6505 *it6505, int offset, u8 *dpcd, int num)
 	return 0;
 }
 
-static void it6505_dump(struct it6505 *it6505)
+static void __maybe_unused it6505_dump(struct it6505 *it6505)
 {
 	unsigned int i, j;
 	u8 regs[16];
@@ -2472,7 +2472,7 @@ static void it6505_link_training_work(struct work_struct *work)
 {
 	struct it6505 *it6505 = container_of(work, struct it6505, link_works);
 	struct device *dev = it6505->dev;
-	int ret;
+	int ret, retry;
 
 	DRM_DEV_DEBUG_DRIVER(dev, "it6505->sink_count: %d",
 			     it6505->sink_count);
@@ -2480,26 +2480,23 @@ static void it6505_link_training_work(struct work_struct *work)
 	if (!it6505_get_sink_hpd_status(it6505))
 		return;
 
-	it6505_link_training_setup(it6505);
-	it6505_reset_hdcp(it6505);
-	it6505_aux_reset(it6505);
-
-	if (it6505->auto_train_retry < 1) {
-		it6505_link_step_train_process(it6505);
-		return;
-	}
+	retry = it6505->auto_train_retry;
+	do {
+		it6505_link_training_setup(it6505);
+		it6505_reset_hdcp(it6505);
+		it6505_aux_reset(it6505);
 
-	ret = it6505_link_start_auto_train(it6505);
-	DRM_DEV_DEBUG_DRIVER(dev, "auto train %s, auto_train_retry: %d",
+		ret = it6505_link_start_auto_train(it6505);
+		DRM_DEV_DEBUG_DRIVER(dev, "auto train %s, auto_train_retry: %d",
 			     ret ? "pass" : "failed", it6505->auto_train_retry);
+		if (ret) {
+			it6505_link_train_ok(it6505);
+			return;
+		}
+	} while (retry--);
 
-	if (ret) {
-		it6505->auto_train_retry = AUTO_TRAIN_RETRY;
-		it6505_link_train_ok(it6505);
-	} else {
-		it6505->auto_train_retry--;
-		it6505_dump(it6505);
-	}
+	/*After HW auto training fail, try link training step by step*/
+	it6505_link_step_train_process(it6505);
 
 }
 

-- 
2.34.1