linux-kernel - [PATCH v2 11/12] drm/bridge: samsung-dsim: samsung_dsim_host_attach: don't use the bridge pointer as an error indicator

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Message-Id: <20260109-drm-bridge-alloc-getput-drm_of_find_bridge-2-v2-11-8bad3ef90b9f@bootlin.com>
Date: Fri, 09 Jan 2026 08:31:42 +0100
From: Luca Ceresoli <luca.ceresoli@...tlin.com>
To: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
 Philippe Cornu <philippe.cornu@...com>, benjamin.gaignard@...aro.org, 
 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>, 
 Adrien Grassein <adrien.grassein@...il.com>, Liu Ying <victor.liu@....com>, 
 Shawn Guo <shawnguo@...nel.org>, Sascha Hauer <s.hauer@...gutronix.de>, 
 Pengutronix Kernel Team <kernel@...gutronix.de>, 
 Fabio Estevam <festevam@...il.com>, Inki Dae <inki.dae@...sung.com>, 
 Jagan Teki <jagan@...rulasolutions.com>, 
 Marek Szyprowski <m.szyprowski@...sung.com>
Cc: Hui Pu <Hui.Pu@...ealthcare.com>, 
 Thomas Petazzoni <thomas.petazzoni@...tlin.com>, 
 dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org, 
 imx@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org, 
 Luca Ceresoli <luca.ceresoli@...tlin.com>
Subject: [PATCH v2 11/12] drm/bridge: samsung-dsim:
 samsung_dsim_host_attach: don't use the bridge pointer as an error
 indicator

In preparation to handle refcounting of the out_bridge, we need to ensure
the out_bridge pointer contains either a valid bridge pointer or NULL, not
an ERR_PTR. Otherwise calls such as drm_bridge_get/put() would try to
redeference an ERR_PTR.

Stop using IS_ERR(next_bridge) as an indication of an error, and instead
use the 'ret' integer.

No functional change.

Acked-by: Maxime Ripard <mripard@...nel.org>
Signed-off-by: Luca Ceresoli <luca.ceresoli@...tlin.com>
---
 drivers/gpu/drm/bridge/samsung-dsim.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/bridge/samsung-dsim.c b/drivers/gpu/drm/bridge/samsung-dsim.c
index 8dd058124e93..afaa63c4d3f7 100644
--- a/drivers/gpu/drm/bridge/samsung-dsim.c
+++ b/drivers/gpu/drm/bridge/samsung-dsim.c
@@ -1891,7 +1891,7 @@ static int samsung_dsim_host_attach(struct mipi_dsi_host *host,
 	struct device_node *np = dev->of_node;
 	struct device_node *remote;
 	struct drm_panel *panel;
-	int ret;
+	int ret = 0;
 
 	/*
 	 * Devices can also be child nodes when we also control that device
@@ -1926,16 +1926,17 @@ static int samsung_dsim_host_attach(struct mipi_dsi_host *host,
 	panel = of_drm_find_panel(remote);
 	if (!IS_ERR(panel)) {
 		next_bridge = devm_drm_panel_bridge_add(dev, panel);
+		if (IS_ERR(next_bridge))
+			ret = PTR_ERR(next_bridge);
 	} else {
 		next_bridge = of_drm_find_bridge(remote);
 		if (!next_bridge)
-			next_bridge = ERR_PTR(-EINVAL);
+			ret = -EINVAL;
 	}
 
 	of_node_put(remote);
 
-	if (IS_ERR(next_bridge)) {
-		ret = PTR_ERR(next_bridge);
+	if (ret) {
 		DRM_DEV_ERROR(dev, "failed to find the bridge: %d\n", ret);
 		return ret;
 	}

-- 
2.52.0