linux-kernel - [PATCH] drm/bridge/panel: Fix runtime warning on panel bridge release

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Message-Id: <20240610102739.139852-1-adam.miotk@arm.com>
Date: Mon, 10 Jun 2024 11:27:39 +0100
From: Adam Miotk <adam.miotk@....com>
To: dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org
Cc: Adam Miotk <adam.miotk@....com>,
	Andrzej Hajda <andrzej.hajda@...el.com>,
	Neil Armstrong <neil.armstrong@...aro.org>,
	Robert Foss <rfoss@...nel.org>,
	Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
	Jonas Karlman <jonas@...boo.se>,
	Jernej Skrabec <jernej.skrabec@...il.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>,
	Smitha T Murthy <smitha.tmurthy@....com>,
	Deepak Pandey <deepak.pandey@....com>
Subject: [PATCH] drm/bridge/panel: Fix runtime warning on panel bridge release

Device managed panel bridge wrappers are created by calling to
drm_panel_bridge_add_typed() and registering a release handler for
clean-up when the device gets unbound.

Since the memory for this bridge is also managed and linked to the panel
device, the release function should not try to free that memory.
Moreover, the call to devm_kfree() inside drm_panel_bridge_remove() will
fail in this case and emit a warning because the panel bridge resource
is no longer on the device resources list (it has been removed from
there before the call to release handlers).

Signed-off-by: Adam Miotk <adam.miotk@....com>
---
 drivers/gpu/drm/bridge/panel.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/bridge/panel.c b/drivers/gpu/drm/bridge/panel.c
index 32506524d9a2..fe5fb08c9fc4 100644
--- a/drivers/gpu/drm/bridge/panel.c
+++ b/drivers/gpu/drm/bridge/panel.c
@@ -360,9 +360,12 @@ EXPORT_SYMBOL(drm_panel_bridge_set_orientation);
 
 static void devm_drm_panel_bridge_release(struct device *dev, void *res)
 {
-	struct drm_bridge **bridge = res;
+	struct drm_bridge *bridge = *(struct drm_bridge **)res;
 
-	drm_panel_bridge_remove(*bridge);
+	if (!bridge)
+		return;
+
+	drm_bridge_remove(bridge);
 }
 
 /**
-- 
2.25.1