From: Luca Ceresoli Date: Tue, 28 Oct 2025 10:15:45 +0000 (+0100) Subject: drm/bridge: add warning for bridges attached without being added X-Git-Tag: v6.19-rc1~157^2~16^2~32 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=76f1a9711b837f90fba91d00e33549ed1364bea2;p=thirdparty%2Fkernel%2Flinux.git drm/bridge: add warning for bridges attached without being added DRM bridges must be added before they are attached. Add a warning to catch violations. The warning is based on the bridge not being part of any list, so it will trigger if the bridge is being attached without ever having been added. It won't catch cases of bridges attached after having been added and then removed, because in that case the bridge will be in bridge_lingering_list. However such a case is both more demanding to detect and less likely to happen, so it can be left unchecked, at least for now. Suggested-by: Maxime Ripard Link: https://lore.kernel.org/all/20250709-sophisticated-loon-of-rain-6ccdd8@houat/ Reviewed-by: Raphael Gallais-Pou Reviewed-by: Maxime Ripard Link: https://patch.msgid.link/20251028-b4-drm-bridge-alloc-add-before-attach-v3-4-bb8611acbbfb@bootlin.com Signed-off-by: Luca Ceresoli --- diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c index 1246a52f8767b..6dba601a056bb 100644 --- a/drivers/gpu/drm/drm_bridge.c +++ b/drivers/gpu/drm/drm_bridge.c @@ -441,6 +441,9 @@ int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge, if (!encoder || !bridge) return -EINVAL; + if (list_empty(&bridge->list)) + DRM_WARN("Missing drm_bridge_add() before attach\n"); + drm_bridge_get(bridge); if (previous && (!previous->dev || previous->encoder != encoder)) {