This series converts all DRM bridge drivers (*) from the now deprecated of_drm_find_bridge() to its replacement of_drm_find_and_get_bridge() which allows correct bridge refcounting. It also converts per-driver "next_bridge" pointers to the unified drm_bridge::next_bridge which puts the reference automatically on bridge deallocation.
This is part of the work to support hotplug of DRM bridges. The grand plan was discussed in [0].
Here's the work breakdown (➜ marks the current series):
1. ➜ add refcounting to DRM bridges struct drm_bridge, based on devm_drm_bridge_alloc() A. ✔ add new alloc API and refcounting (v6.16) B. ✔ convert all bridge drivers to new API (v6.17) C. ✔ kunit tests (v6.17) D. ✔ add get/put to drm_bridge_add/remove() + attach/detach() and warn on old allocation pattern (v6.17) E. ➜ add get/put on drm_bridge accessors 1. ✔ drm_bridge_chain_get_first_bridge(), add cleanup action (v6.18) 2. ✔ drm_bridge_get_prev_bridge() (v6.18) 3. ✔ drm_bridge_get_next_bridge() (v6.19) 4. ✔ drm_for_each_bridge_in_chain() (v6.19) 5. ✔ drm_bridge_connector_init (v6.19) 6. … protect encoder bridge chain with a mutex 7. ➜ of_drm_find_bridge a. ✔… add of_drm_get_bridge(), convert basic direct users (v6.20?, one driver still pending) b. ➜ convert direct of_drm_get_bridge() users, part 2 c. convert direct of_drm_get_bridge() users, part 3 d. convert direct of_drm_get_bridge() users, part 4 e. convert bridge-only drm_of_find_panel_or_bridge() users 8. drm_of_find_panel_or_bridge, *_of_get_bridge 9. ✔ enforce drm_bridge_add before drm_bridge_attach (v6.19) F. ✔ debugfs improvements 1. ✔ add top-level 'bridges' file (v6.16) 2. ✔ show refcount and list lingering bridges (v6.19) 2. … handle gracefully atomic updates during bridge removal A. ✔ Add drm_dev_enter/exit() to protect device resources (v6.20?) B. … protect private_obj removal from list 3. … DSI host-device driver interaction 4. ✔ removing the need for the "always-disconnected" connector 5. finish the hotplug bridge work, moving code to the core and potentially removing the hotplug-bridge itself (this needs to be clarified as points 1-3 are developed)
[0] https://lore.kernel.org/lkml/20250206-hotplug-drm-bridge-v6-0-9d6f2c9c3058@b...
This work is a continuation of the work to correctly handle bridge refcounting for existing of_drm_find_bridge(). The ground work is in:
- commit 293a8fd7721a ("drm/bridge: add of_drm_find_and_get_bridge()") - commit 9da0e06abda8 ("drm/bridge: deprecate of_drm_find_bridge()") - commit 3fdeae134ba9 ("drm/bridge: add next_bridge pointer to struct drm_bridge")
The whole conversion is split in multiple series to make the review process a bit smoother. Parts 3 and 4 are converting non-bridge drivers (mostly encoders).
(*) One bridge driver (synopsys/dw-hdmi) is converted in another series, together with its (non-bridge) users. Additionally this series converts drm_of_panel_bridge_remove() which is a special case, and has a bugfix for it too.
Signed-off-by: Luca Ceresoli luca.ceresoli@bootlin.com --- Luca Ceresoli (12): drm: of: drm_of_panel_bridge_remove(): fix device_node leak drm: of: drm_of_panel_bridge_remove(): convert to of_drm_find_and_get_bridge() drm/bridge: sii902x: convert to of_drm_find_and_get_bridge() drm/bridge: thc63lvd1024: convert to of_drm_find_and_get_bridge() drm/bridge: tfp410: convert to of_drm_find_and_get_bridge() drm/bridge: tpd12s015: convert to of_drm_find_and_get_bridge() drm/bridge: lt8912b: convert to of_drm_find_and_get_bridge() drm/bridge: imx8mp-hdmi-pvi: convert to of_drm_find_and_get_bridge() drm/bridge: imx8qxp-ldb: convert to of_drm_find_and_get_bridge() drm/bridge: samsung-dsim: samsung_dsim_host_attach: use a temporary variable for the next bridge drm/bridge: samsung-dsim: samsung_dsim_host_attach: don't use the bridge pointer as an error indicator drm/bridge: samsung-dsim: samsung_dsim_host_attach: convert to of_drm_find_and_get_bridge()
drivers/gpu/drm/bridge/imx/imx8mp-hdmi-pvi.c | 15 +++++++------- drivers/gpu/drm/bridge/imx/imx8qxp-ldb.c | 3 ++- drivers/gpu/drm/bridge/lontium-lt8912b.c | 31 ++++++++++++++-------------- drivers/gpu/drm/bridge/samsung-dsim.c | 28 ++++++++++++++++--------- drivers/gpu/drm/bridge/sii902x.c | 7 +++---- drivers/gpu/drm/bridge/thc63lvd1024.c | 7 +++---- drivers/gpu/drm/bridge/ti-tfp410.c | 27 ++++++++++++------------ drivers/gpu/drm/bridge/ti-tpd12s015.c | 8 +++---- include/drm/bridge/samsung-dsim.h | 1 - include/drm/drm_of.h | 6 +++++- 10 files changed, 69 insertions(+), 64 deletions(-) --- base-commit: 2bcba510a612cea32b8a536eedeabd7fcb413cd0 change-id: 20251223-drm-bridge-alloc-getput-drm_of_find_bridge-2-12c6bbcb6896
Best regards,
drm_of_panel_bridge_remove() uses of_graph_get_remote_node() to get a device_node but does not put the node reference.
Fixes: c70087e8f16f ("drm/drm_of: add drm_of_panel_bridge_remove function") Cc: stable@vger.kernel.org # v4.15 Signed-off-by: Luca Ceresoli luca.ceresoli@bootlin.com --- include/drm/drm_of.h | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/include/drm/drm_of.h b/include/drm/drm_of.h index 7f0256dae3f1..f3e55ea2174c 100644 --- a/include/drm/drm_of.h +++ b/include/drm/drm_of.h @@ -5,6 +5,7 @@ #include <linux/err.h> #include <linux/of_graph.h> #if IS_ENABLED(CONFIG_OF) && IS_ENABLED(CONFIG_DRM_PANEL_BRIDGE) +#include <linux/of.h> #include <drm/drm_bridge.h> #endif
@@ -173,6 +174,8 @@ static inline int drm_of_panel_bridge_remove(const struct device_node *np, bridge = of_drm_find_bridge(remote); drm_panel_bridge_remove(bridge);
+ of_node_put(remote); + return 0; #else return -EINVAL;
On Wed, 7 Jan 2026 14:12:52 +0100, Luca Ceresoli wrote:
drm_of_panel_bridge_remove() uses of_graph_get_remote_node() to get a device_node but does not put the node reference.
Fixes: c70087e8f16f ("drm/drm_of: add drm_of_panel_bridge_remove function") Cc: stable@vger.kernel.org # v4.15
[ ... ]
Acked-by: Maxime Ripard mripard@kernel.org
Thanks! Maxime
On 07.01.2026 14:12, Luca Ceresoli wrote:
This series converts all DRM bridge drivers (*) from the now deprecated of_drm_find_bridge() to its replacement of_drm_find_and_get_bridge() which allows correct bridge refcounting. It also converts per-driver "next_bridge" pointers to the unified drm_bridge::next_bridge which puts the reference automatically on bridge deallocation.
This is part of the work to support hotplug of DRM bridges. The grand plan was discussed in [0].
This patchset breaks Exynos DSI (Samsung-DSIM) driver operation on all my test boards. I will try to debug it and provide more information tomorrow though.
Here's the work breakdown (➜ marks the current series):
- ➜ add refcounting to DRM bridges struct drm_bridge, based on devm_drm_bridge_alloc() A. ✔ add new alloc API and refcounting (v6.16) B. ✔ convert all bridge drivers to new API (v6.17) C. ✔ kunit tests (v6.17) D. ✔ add get/put to drm_bridge_add/remove() + attach/detach() and warn on old allocation pattern (v6.17) E. ➜ add get/put on drm_bridge accessors
b. ➜ convert direct of_drm_get_bridge() users, part 2 c. convert direct of_drm_get_bridge() users, part 3 d. convert direct of_drm_get_bridge() users, part 4 e. convert bridge-only drm_of_find_panel_or_bridge() users 8. drm_of_find_panel_or_bridge, *_of_get_bridge 9. ✔ enforce drm_bridge_add before drm_bridge_attach (v6.19) F. ✔ debugfs improvements
- ✔ drm_bridge_chain_get_first_bridge(), add cleanup action (v6.18)
- ✔ drm_bridge_get_prev_bridge() (v6.18)
- ✔ drm_bridge_get_next_bridge() (v6.19)
- ✔ drm_for_each_bridge_in_chain() (v6.19)
- ✔ drm_bridge_connector_init (v6.19)
- … protect encoder bridge chain with a mutex
- ➜ of_drm_find_bridge a. ✔… add of_drm_get_bridge(), convert basic direct users (v6.20?, one driver still pending)
- ✔ add top-level 'bridges' file (v6.16)
- ✔ show refcount and list lingering bridges (v6.19)
- … handle gracefully atomic updates during bridge removal A. ✔ Add drm_dev_enter/exit() to protect device resources (v6.20?) B. … protect private_obj removal from list
- … DSI host-device driver interaction
- ✔ removing the need for the "always-disconnected" connector
- finish the hotplug bridge work, moving code to the core and potentially removing the hotplug-bridge itself (this needs to be clarified as points 1-3 are developed)
[0] https://lore.kernel.org/lkml/20250206-hotplug-drm-bridge-v6-0-9d6f2c9c3058@b...
This work is a continuation of the work to correctly handle bridge refcounting for existing of_drm_find_bridge(). The ground work is in:
- commit 293a8fd7721a ("drm/bridge: add of_drm_find_and_get_bridge()")
- commit 9da0e06abda8 ("drm/bridge: deprecate of_drm_find_bridge()")
- commit 3fdeae134ba9 ("drm/bridge: add next_bridge pointer to struct drm_bridge")
The whole conversion is split in multiple series to make the review process a bit smoother. Parts 3 and 4 are converting non-bridge drivers (mostly encoders).
(*) One bridge driver (synopsys/dw-hdmi) is converted in another series, together with its (non-bridge) users. Additionally this series converts drm_of_panel_bridge_remove() which is a special case, and has a bugfix for it too.
Signed-off-by: Luca Ceresoli luca.ceresoli@bootlin.com
Luca Ceresoli (12): drm: of: drm_of_panel_bridge_remove(): fix device_node leak drm: of: drm_of_panel_bridge_remove(): convert to of_drm_find_and_get_bridge() drm/bridge: sii902x: convert to of_drm_find_and_get_bridge() drm/bridge: thc63lvd1024: convert to of_drm_find_and_get_bridge() drm/bridge: tfp410: convert to of_drm_find_and_get_bridge() drm/bridge: tpd12s015: convert to of_drm_find_and_get_bridge() drm/bridge: lt8912b: convert to of_drm_find_and_get_bridge() drm/bridge: imx8mp-hdmi-pvi: convert to of_drm_find_and_get_bridge() drm/bridge: imx8qxp-ldb: convert to of_drm_find_and_get_bridge() drm/bridge: samsung-dsim: samsung_dsim_host_attach: use a temporary variable for the next bridge drm/bridge: samsung-dsim: samsung_dsim_host_attach: don't use the bridge pointer as an error indicator drm/bridge: samsung-dsim: samsung_dsim_host_attach: convert to of_drm_find_and_get_bridge()
drivers/gpu/drm/bridge/imx/imx8mp-hdmi-pvi.c | 15 +++++++------- drivers/gpu/drm/bridge/imx/imx8qxp-ldb.c | 3 ++- drivers/gpu/drm/bridge/lontium-lt8912b.c | 31 ++++++++++++++-------------- drivers/gpu/drm/bridge/samsung-dsim.c | 28 ++++++++++++++++--------- drivers/gpu/drm/bridge/sii902x.c | 7 +++---- drivers/gpu/drm/bridge/thc63lvd1024.c | 7 +++---- drivers/gpu/drm/bridge/ti-tfp410.c | 27 ++++++++++++------------ drivers/gpu/drm/bridge/ti-tpd12s015.c | 8 +++---- include/drm/bridge/samsung-dsim.h | 1 - include/drm/drm_of.h | 6 +++++- 10 files changed, 69 insertions(+), 64 deletions(-)
base-commit: 2bcba510a612cea32b8a536eedeabd7fcb413cd0 change-id: 20251223-drm-bridge-alloc-getput-drm_of_find_bridge-2-12c6bbcb6896
Best regards,
Best regards
linux-stable-mirror@lists.linaro.org
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Luca Ceresoli -
Marek Szyprowski -
Maxime Ripard