linux-kernel - [PATCH] drm/radeon: Delay Connector detecting when HPD singals is unstable

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Date: Thu,  9 May 2024 16:57:58 +0800
From: oushixiong <oushixiong@...inos.cn>
To: Alex Deucher <alexander.deucher@....com>
Cc: Christian König <christian.koenig@....com>,
	David Airlie <airlied@...il.com>,
	Daniel Vetter <daniel@...ll.ch>,
	amd-gfx@...ts.freedesktop.org,
	dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org,
	Xinhui.Pan@....com,
	Shixiong Ou <oushixiong@...inos.cn>
Subject: [PATCH] drm/radeon: Delay Connector detecting when HPD singals is unstable

From: Shixiong Ou <oushixiong@...inos.cn>

In some causes, HPD signals will jitter when plugging in
or unplugging HDMI.

Rescheduling the hotplug work for a second when EDID may still be
readable but HDP is disconnected, and fixes this issue.

Signed-off-by: Shixiong Ou <oushixiong@...inos.cn>
---
 drivers/gpu/drm/radeon/radeon_connectors.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/gpu/drm/radeon/radeon_connectors.c b/drivers/gpu/drm/radeon/radeon_connectors.c
index b84b58926106..cf0114ca59a4 100644
--- a/drivers/gpu/drm/radeon/radeon_connectors.c
+++ b/drivers/gpu/drm/radeon/radeon_connectors.c
@@ -1267,6 +1267,16 @@ radeon_dvi_detect(struct drm_connector *connector, bool force)
 			goto exit;
 		}
 	}
+
+	if (dret && radeon_connector->hpd.hpd != RADEON_HPD_NONE &&
+	    !radeon_hpd_sense(rdev, radeon_connector->hpd.hpd) &&
+	    connector->connector_type == DRM_MODE_CONNECTOR_HDMIA) {
+		DRM_DEBUG_KMS("EDID is readable when HPD disconnected\n");
+		schedule_delayed_work(&rdev->hotplug_work, msecs_to_jiffies(1000));
+		ret = connector_status_disconnected;
+		goto exit;
+	}
+
 	if (dret) {
 		radeon_connector->detected_by_load = false;
 		radeon_connector_free_edid(connector);
-- 
2.17.1