linux-kernel - [PATCH v3 5/5] drm/bridge: it6505: skip auto training when previous try fail

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Message-Id: <20250401-fix-link-training-v3-5-7f60f2ab7b8c@ite.com.tw>
Date: Tue, 01 Apr 2025 15:54:59 +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 v3 5/5] drm/bridge: it6505: skip auto training when
 previous try fail

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

When connect to device which can only training done by
step training, skip auto training when link training restart,
usually happen when display resolution is changed.

Signed-off-by: Hermes Wu <Hermes.wu@....com.tw>
---
 drivers/gpu/drm/bridge/ite-it6505.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/bridge/ite-it6505.c b/drivers/gpu/drm/bridge/ite-it6505.c
index bff5f18fb5ae7192242308f034b60af9807c192c..20eae23cb46a4cb3fc18dd2ed3b764f2265262ca 100644
--- a/drivers/gpu/drm/bridge/ite-it6505.c
+++ b/drivers/gpu/drm/bridge/ite-it6505.c
@@ -467,6 +467,7 @@ struct it6505 {
 	struct delayed_work hdcp_work;
 	struct work_struct hdcp_wait_ksv_list;
 	struct completion extcon_completion;
+	u8 step_train_only;
 	bool hdcp_desired;
 	bool is_repeater;
 	u8 hdcp_down_stream_count;
@@ -2452,11 +2453,13 @@ static void it6505_link_step_train_process(struct it6505 *it6505)
 				     ret ? "pass" : "failed", i + 1);
 		if (ret) {
 			it6505_link_train_ok(it6505);
+			it6505->step_train_only = true;
 			return;
 		}
 	}
 
 	DRM_DEV_DEBUG_DRIVER(dev, "training fail");
+	it6505->step_train_only = false;
 	it6505->link_state = LINK_IDLE;
 	it6505_video_reset(it6505);
 }
@@ -2473,14 +2476,14 @@ static void it6505_link_training_work(struct work_struct *work)
 	if (!it6505_get_sink_hpd_status(it6505))
 		return;
 
-	for (retry = AUTO_TRAIN_RETRY; retry > 0; retry--) {
+	for (retry = AUTO_TRAIN_RETRY; retry > 0 && !it6505->step_train_only; retry--) {
 		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,",
-				     ret ? "pass" : "failed");
+					ret ? "pass" : "failed");
 		if (ret) {
 			it6505_link_train_ok(it6505);
 			return;
@@ -2594,6 +2597,7 @@ static void it6505_irq_hpd(struct it6505 *it6505)
 			it6505_variable_config(it6505);
 			it6505_parse_link_capabilities(it6505);
 		}
+		it6505->step_train_only = false;
 
 		it6505_drm_dp_link_set_power(&it6505->aux, &it6505->link,
 					     DP_SET_POWER_D0);

-- 
2.34.1