linux-kernel - [PATCH] drm: xlnx: zynqmp_dpsub: Fix missing drm_bridge

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Message-Id: <20240312-xilinx-dp-lock-fix-v1-1-1698f9f03bac@ideasonboard.com>
Date: Tue, 12 Mar 2024 10:51:15 +0200
From: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
To: Laurent Pinchart <laurent.pinchart@...asonboard.com>, 
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
 David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>, 
 Michal Simek <michal.simek@....com>
Cc: dri-devel@...ts.freedesktop.org, linux-arm-kernel@...ts.infradead.org, 
 linux-kernel@...r.kernel.org, Vishal Sagar <vishal.sagar@....com>, 
 Anatoliy Klymenko <anatoliy.klymenko@....com>, 
 Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
Subject: [PATCH] drm: xlnx: zynqmp_dpsub: Fix missing drm_bridge_add() call

The driver creates a bridge, but never calls drm_bridge_add() when
non-live input is used. This leaves the bridge's hpd_mutex
uninitialized, leading to:

WARNING: CPU: 0 PID: 9 at kernel/locking/mutex.c:582 __mutex_lock+0x708/0x840

Add the bridge add & remove calls so that the bridge gets managed
correctly.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
Fixes: 561671612394 ("drm: xlnx: zynqmp_dpsub: Add support for live video input")
---
 drivers/gpu/drm/xlnx/zynqmp_dp.c    | 4 ++++
 drivers/gpu/drm/xlnx/zynqmp_dpsub.c | 4 ----
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/xlnx/zynqmp_dp.c b/drivers/gpu/drm/xlnx/zynqmp_dp.c
index a0606fab0e22..9f750740dfb8 100644
--- a/drivers/gpu/drm/xlnx/zynqmp_dp.c
+++ b/drivers/gpu/drm/xlnx/zynqmp_dp.c
@@ -1761,6 +1761,8 @@ int zynqmp_dp_probe(struct zynqmp_dpsub *dpsub)
 
 	dpsub->dp = dp;
 
+	drm_bridge_add(dpsub->bridge);
+
 	dev_dbg(dp->dev, "ZynqMP DisplayPort Tx probed with %u lanes\n",
 		dp->num_lanes);
 
@@ -1789,4 +1791,6 @@ void zynqmp_dp_remove(struct zynqmp_dpsub *dpsub)
 
 	zynqmp_dp_phy_exit(dp);
 	zynqmp_dp_reset(dp, true);
+
+	drm_bridge_remove(dpsub->bridge);
 }
diff --git a/drivers/gpu/drm/xlnx/zynqmp_dpsub.c b/drivers/gpu/drm/xlnx/zynqmp_dpsub.c
index 88eb33acd5f0..3933c4f1a44f 100644
--- a/drivers/gpu/drm/xlnx/zynqmp_dpsub.c
+++ b/drivers/gpu/drm/xlnx/zynqmp_dpsub.c
@@ -260,8 +260,6 @@ static int zynqmp_dpsub_probe(struct platform_device *pdev)
 		ret = zynqmp_dpsub_drm_init(dpsub);
 		if (ret)
 			goto err_disp;
-	} else {
-		drm_bridge_add(dpsub->bridge);
 	}
 
 	dev_info(&pdev->dev, "ZynqMP DisplayPort Subsystem driver probed");
@@ -288,8 +286,6 @@ static void zynqmp_dpsub_remove(struct platform_device *pdev)
 
 	if (dpsub->drm)
 		zynqmp_dpsub_drm_cleanup(dpsub);
-	else
-		drm_bridge_remove(dpsub->bridge);
 
 	zynqmp_disp_remove(dpsub);
 	zynqmp_dp_remove(dpsub);

---
base-commit: e8f897f4afef0031fe618a8e94127a0934896aba
change-id: 20240312-xilinx-dp-lock-fix-cf68f43a7bab

Best regards,
-- 
Tomi Valkeinen <tomi.valkeinen@...asonboard.com>