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 --- Changes in v2: - Fix bug in samsung-dsim code, patch 10; update patch 12 on top of those changes - Fix in imx8qxp-ldb code, patch 9 - Link to v1: https://lore.kernel.org/r/20260107-drm-bridge-alloc-getput-drm_of_find_bridg...
--- 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 | 12 ++++++++- drivers/gpu/drm/bridge/lontium-lt8912b.c | 31 +++++++++++------------ drivers/gpu/drm/bridge/samsung-dsim.c | 37 +++++++++++++++++++--------- 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, 86 insertions(+), 65 deletions(-) --- base-commit: 814b88f91b121246b35be9c519b537041fe3d178 change-id: 20251223-drm-bridge-alloc-getput-drm_of_find_bridge-2-12c6bbcb6896
Best regards,