[PATCH 3/5] drm/msm/dp: suppress bridge hotplug events during MST operation

From: Yongxing Mou <yongxing.mou@oss.qualcomm.com>
To: Andrzej Hajda <andrzej.hajda@intel.com>,
	Neil Armstrong <neil.armstrong@linaro.org>,
	Robert Foss <rfoss@kernel.org>,
	Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
	Jonas Karlman <jonas@kwiboo.se>,
	Jernej Skrabec <jernej.skrabec@gmail.com>,
	Luca Ceresoli <luca.ceresoli@bootlin.com>,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Maxime Ripard <mripard@kernel.org>,
	Thomas Zimmermann <tzimmermann@suse.de>,
	David Airlie <airlied@gmail.com>, Simona Vetter <simona@ffwll.ch>,
	Kevin Hilman <khilman@baylibre.com>,
	Jerome Brunet <jbrunet@baylibre.com>,
	Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
	Rob Clark <robin.clark@oss.qualcomm.com>,
	Dmitry Baryshkov <lumag@kernel.org>,
	Abhinav Kumar <abhinav.kumar@linux.dev>,
	Jessica Zhang <jesszhan0024@gmail.com>,
	Sean Paul <sean@poorly.run>,
	Marijn Suijten <marijn.suijten@somainline.org>,
	Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>,
	Bjorn Andersson <andersson@kernel.org>,
	Konrad Dybcio <konradybcio@kernel.org>
Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
	linux-amlogic@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org,
	linux-arm-msm@vger.kernel.org, freedreno@lists.freedesktop.org,
	Yongxing Mou <yongxing.mou@oss.qualcomm.com>
Subject: [PATCH 3/5] drm/msm/dp: suppress bridge hotplug events during MST operation
Date: Mon, 29 Jun 2026 22:48:05 +0800	[thread overview]
Message-ID: <20260629-msm-dp-msttypec-v1-3-646a10256233@oss.qualcomm.com> (raw)
In-Reply-To: <20260629-msm-dp-msttypec-v1-0-646a10256233@oss.qualcomm.com>

The DP MST framework already generates the required hotplug events for
MST topology changes.

Suppress connector hotplug event generation from the bridge connector
path while MST is active, and continue propagating HPD notifications to
the DP driver.

Signed-off-by: Yongxing Mou <yongxing.mou@oss.qualcomm.com>
---
 drivers/gpu/drm/display/drm_bridge_connector.c | 6 ++++--
 drivers/gpu/drm/msm/dp/dp_display.c            | 9 ++++++++-
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/display/drm_bridge_connector.c b/drivers/gpu/drm/display/drm_bridge_connector.c
index 7334d6677604..82ed0dc450ab 100644
--- a/drivers/gpu/drm/display/drm_bridge_connector.c
+++ b/drivers/gpu/drm/display/drm_bridge_connector.c
@@ -162,6 +162,7 @@ static void drm_bridge_connector_handle_hpd(struct drm_bridge_connector *drm_bri
 {
 	struct drm_connector *connector = &drm_bridge_connector->base;
 	struct drm_device *dev = connector->dev;
+	bool send_hotplug = true;
 
 	/*
 	 * IRQ-only notification: extra_status carries the event but
@@ -179,9 +180,10 @@ static void drm_bridge_connector_handle_hpd(struct drm_bridge_connector *drm_bri
 	connector->status = status;
 	mutex_unlock(&dev->mode_config.mutex);
 
-	drm_bridge_connector_hpd_notify(connector, status, extra_status, NULL);
+	drm_bridge_connector_hpd_notify(connector, status, extra_status, &send_hotplug);
 
-	drm_kms_helper_connector_hotplug_event(connector);
+	if (send_hotplug)
+		drm_kms_helper_connector_hotplug_event(connector);
 }
 
 static void drm_bridge_connector_hpd_cb(void *cb_data,
diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
index 6835c68fe510..bc93b566fbca 100644
--- a/drivers/gpu/drm/msm/dp/dp_display.c
+++ b/drivers/gpu/drm/msm/dp/dp_display.c
@@ -1790,10 +1790,17 @@ void msm_dp_bridge_hpd_notify(struct drm_bridge *bridge,
 			msm_dp_hpd_plug_handle(dp);
 		} else {
 			msm_dp_hpd_plug_handle(dp);
+			/* mst_active is set in plug_handle; suppress SST hotplug */
+			if (send_hotplug && msm_dp_display->mst_active)
+				*send_hotplug = false;
 		}
 	} else {
-		if (hpd_link_status == ISR_DISCONNECTED)
+		if (!msm_dp_display->mst_active) {
 			msm_dp_hpd_unplug_handle(dp);
+		} else if (send_hotplug) {
+			msm_dp_hpd_unplug_handle(dp);
+			*send_hotplug = false;
+		}
 	}
 
 	pm_runtime_put_sync(&msm_dp_display->pdev->dev);

-- 
2.43.0


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