linux-kernel - [PATCH v4 drm-dp 02/11] drm/hisilicon/hibmc: fix dp probabilistical detect errors after HPD irq

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Message-ID: <20250813094238.3722345-3-shiyongbang@huawei.com>
Date: Wed, 13 Aug 2025 17:42:29 +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>, <libaihan@...wei.com>,
	<shenjian15@...wei.com>, <shaojijie@...wei.com>,
	<dri-devel@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH v4 drm-dp 02/11] drm/hisilicon/hibmc: fix dp probabilistical detect errors after HPD irq

From: Baihan Li <libaihan@...wei.com>

The debouncing when HPD pulled out still remains sometimes, 200ms still can
not ensure helper_detect() is correct. So add a flag to hold the sink
status, and changed detect_ctx() functions by using flag to check status.

Fixes: 3c7623fb5bb6 ("drm/hisilicon/hibmc: Enable this hot plug detect of irq feature")
Signed-off-by: Baihan Li <libaihan@...wei.com>
Signed-off-by: Yongbang Shi <shiyongbang@...wei.com>
---
ChangeLog:
v3 -> v4:
  - remove link training process in hibmc_dp_detect(), suggested by Dmitry Baryshkov.
  - remove if (dev->registered), suggested by Dmitry Baryshkov.
---
 drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h    |  1 +
 .../gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c    | 19 ++++++++++++-------
 2 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h
index 665f5b166dfb..68867475508c 100644
--- a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h
+++ b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h
@@ -50,6 +50,7 @@ struct hibmc_dp {
 	struct drm_dp_aux aux;
 	struct hibmc_dp_cbar_cfg cfg;
 	u32 irq_status;
+	int hpd_status;
 };
 
 int hibmc_dp_hw_init(struct hibmc_dp *dp);
diff --git a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c
index d06832e62e96..ded38530ecda 100644
--- a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c
+++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c
@@ -34,9 +34,12 @@ static int hibmc_dp_connector_get_modes(struct drm_connector *connector)
 static int hibmc_dp_detect(struct drm_connector *connector,
 			   struct drm_modeset_acquire_ctx *ctx, bool force)
 {
-	mdelay(200);
+	struct hibmc_dp *dp = to_hibmc_dp(connector);
 
-	return drm_connector_helper_detect_from_ddc(connector, ctx, force);
+	if (dp->hpd_status)
+		return connector_status_connected;
+	else
+		return connector_status_disconnected;
 }
 
 static const struct drm_connector_helper_funcs hibmc_dp_conn_helper_funcs = {
@@ -115,21 +118,23 @@ irqreturn_t hibmc_dp_hpd_isr(int irq, void *arg)
 {
 	struct drm_device *dev = (struct drm_device *)arg;
 	struct hibmc_drm_private *priv = to_hibmc_drm_private(dev);
+	struct hibmc_dp *dp = &priv->dp;
 	int idx;
 
 	if (!drm_dev_enter(dev, &idx))
 		return -ENODEV;
 
-	if (priv->dp.irq_status & DP_MASKED_SINK_HPD_PLUG_INT) {
+	if (((dp->irq_status & DP_MASKED_SINK_HPD_PLUG_INT) && !dp->hpd_status)) {
 		drm_dbg_dp(&priv->dev, "HPD IN isr occur!\n");
-		hibmc_dp_hpd_cfg(&priv->dp);
+		hibmc_dp_hpd_cfg(dp);
+		dp->hpd_status = 1;
 	} else {
 		drm_dbg_dp(&priv->dev, "HPD OUT isr occur!\n");
-		hibmc_dp_reset_link(&priv->dp);
+		hibmc_dp_reset_link(dp);
+		dp->hpd_status = 0;
 	}
 
-	if (dev->registered)
-		drm_connector_helper_hpd_irq_event(&priv->dp.connector);
+	drm_connector_helper_hpd_irq_event(&priv->dp.connector);
 
 	drm_dev_exit(idx);
 
-- 
2.33.0