linux-kernel - [PATCH drm-dp 1/4] drm/hisilicon/hibmc: add updating link cap in DP detect()

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Message-ID: <20260207094837.1468985-2-shiyongbang@huawei.com>
Date: Sat, 7 Feb 2026 17:48:34 +0800
From: Yongbang Shi <shiyongbang@...wei.com>
To: <xinliang.liu@...aro.org>, <tiantao6@...ilicon.com>,
	<maarten.lankhorst@...ux.intel.com>, <mripard@...nel.org>,
	<tzimmermann@...e.de>, <airlied@...il.com>, <daniel@...ll.ch>,
	<kong.kongxinwei@...ilicon.com>, <dmitry.baryshkov@....qualcomm.com>
CC: <liangjian010@...wei.com>, <chenjianmin@...wei.com>,
	<fengsheng5@...wei.com>, <shiyongbang@...wei.com>, <helin52@...artners.com>,
	<shenjian15@...wei.com>, <shaojijie@...wei.com>,
	<dri-devel@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH drm-dp 1/4] drm/hisilicon/hibmc: add updating link cap in DP detect()

From: Lin He <helin52@...wei.com>

In the past, the link cap is updated in link training at encoder enable
stage, but the hibmc_dp_mode_valid() is called before it, which will use
DP link's rate and lanes. So add the hibmc_dp_update_caps() in
hibmc_dp_update_caps() to avoid some potential risks.

Fixes: e6c7c59da494 ("drm/hisilicon/hibmc: add dp mode valid check")
Signed-off-by: Lin He <helin52@...wei.com>
Signed-off-by: Yongbang Shi <shiyongbang@...wei.com>
---
 drivers/gpu/drm/hisilicon/hibmc/dp/dp_comm.h   | 1 +
 drivers/gpu/drm/hisilicon/hibmc/dp/dp_link.c   | 2 +-
 drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c | 2 ++
 3 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_comm.h b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_comm.h
index f9ee7ebfec55..f53dac256ee0 100644
--- a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_comm.h
+++ b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_comm.h
@@ -69,5 +69,6 @@ int hibmc_dp_link_training(struct hibmc_dp_dev *dp);
 int hibmc_dp_serdes_init(struct hibmc_dp_dev *dp);
 int hibmc_dp_serdes_rate_switch(u8 rate, struct hibmc_dp_dev *dp);
 int hibmc_dp_serdes_set_tx_cfg(struct hibmc_dp_dev *dp, u8 train_set[HIBMC_DP_LANE_NUM_MAX]);
+void hibmc_dp_update_caps(struct hibmc_dp_dev *dp);
 
 #endif
diff --git a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_link.c b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_link.c
index 0726cb5b736e..8c53f16db516 100644
--- a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_link.c
+++ b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_link.c
@@ -325,7 +325,7 @@ static int hibmc_dp_link_downgrade_training_eq(struct hibmc_dp_dev *dp)
 	return hibmc_dp_link_reduce_rate(dp);
 }
 
-static void hibmc_dp_update_caps(struct hibmc_dp_dev *dp)
+void hibmc_dp_update_caps(struct hibmc_dp_dev *dp)
 {
 	dp->link.cap.link_rate = dp->dpcd[DP_MAX_LINK_RATE];
 	if (dp->link.cap.link_rate > DP_LINK_BW_8_1 || !dp->link.cap.link_rate)
diff --git a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c
index 616821e3c933..35dff7bfbf76 100644
--- a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c
+++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c
@@ -41,6 +41,8 @@ static bool hibmc_dp_get_dpcd(struct hibmc_dp_dev *dp_dev)
 	if (ret)
 		return false;
 
+	hibmc_dp_update_caps(dp_dev);
+
 	dp_dev->is_branch = drm_dp_is_branch(dp_dev->dpcd);
 
 	ret = drm_dp_read_desc(dp_dev->aux, &dp_dev->desc, dp_dev->is_branch);
-- 
2.33.0