From: Luca Ceresoli <luca.ceresoli@bootlin.com>
Date: Fri, 20 Jun 2025 15:59:54 +0000 (+0200)
Subject: drm/bridge: get/put the bridge reference in drm_bridge_attach/detach()
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=94d50c1a2ca31d80f12d9c2bdbc41437751e320c;p=thirdparty%2Flinux.git

drm/bridge: get/put the bridge reference in drm_bridge_attach/detach()

drm_bridge_attach() adds the bridge to the encoder chain, so take a
reference for that. Vice versa in drm_bridge_detach().

Reviewed-by: Maxime Ripard <mripard@kernel.org>
Link: https://lore.kernel.org/r/20250620-drm-bridge-alloc-getput-drm-bridge-c-v9-2-ca53372c9a84@bootlin.com
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
---

diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
index fa2b2457b16e1..f001bbe95559a 100644
--- a/drivers/gpu/drm/drm_bridge.c
+++ b/drivers/gpu/drm/drm_bridge.c
@@ -411,11 +411,17 @@ int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge,
 	if (!encoder || !bridge)
 		return -EINVAL;
 
-	if (previous && (!previous->dev || previous->encoder != encoder))
-		return -EINVAL;
+	drm_bridge_get(bridge);
 
-	if (bridge->dev)
-		return -EBUSY;
+	if (previous && (!previous->dev || previous->encoder != encoder)) {
+		ret = -EINVAL;
+		goto err_put_bridge;
+	}
+
+	if (bridge->dev) {
+		ret = -EBUSY;
+		goto err_put_bridge;
+	}
 
 	bridge->dev = encoder->dev;
 	bridge->encoder = encoder;
@@ -464,6 +470,8 @@ err_reset_bridge:
 			      "failed to attach bridge %pOF to encoder %s\n",
 			      bridge->of_node, encoder->name);
 
+err_put_bridge:
+	drm_bridge_put(bridge);
 	return ret;
 }
 EXPORT_SYMBOL(drm_bridge_attach);
@@ -484,6 +492,7 @@ void drm_bridge_detach(struct drm_bridge *bridge)
 
 	list_del(&bridge->chain_node);
 	bridge->dev = NULL;
+	drm_bridge_put(bridge);
 }
 
 /**