[PATCH v3 0/4] drm/bridge: convert users of of_drm_find_bridge(), part 4

Luca Ceresoli
2026-03-18T09:39:55Z

This series converts many DRM drivers from the now deprecated
of_drm_find_bridge() to its replacement of_drm_find_and_get_bridge() which
allows correct bridge refcounting.

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() (v7.0),
convert basic direct users (v7.0-v7.1)
b. ✔ convert direct of_drm_get_bridge() users, part 2 (v7.0)
c. ✔ convert direct of_drm_get_bridge() users, part 3 (v7.0)
d. ➜ convert direct of_drm_get_bridge() users, part 4
(some v7.1, some pending)
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
C. … Add drm_bridge_clear_and_put()
3. … DSI host-device driver interaction
4. ✔ removing the need for the "always-disconnected" connector
5. Migrate i.MX LCDIF driver to bridge-connector
6. DRM bridge hotplug
A. Bridge hotplug management in the DRM core
B. Device tree description

[0] https://lore.kernel.org/lkml/20250206-hotplug-drm-bridge-v6-0-9d6f2c9c3058@bootlin.com/#t

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:

- Part 2: mostly drivers in drivers/gpu/drm/bridge [2], applied
- Part 3: other drivers, low-medium complexity [3], applied
- Part 4: other drivers, converting the most complex cases [this series]

[2] https://lore.kernel.org/lkml/20260109-drm-bridge-alloc-getput-drm_of_find_bridge-2-v2-0-8bad3ef90b9f@bootlin.com/
[3] https://lore.kernel.org/lkml/20260109-drm-bridge-alloc-getput-drm_of_find_bridge-3-v2-0-8d7a3dbacdf4@bootlin.com/

Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
---
Changes in v3:
- Rebased on current drm-misc-next (on v7.0-rc3)
- Dropped patches already applied
- Link to v2: https://lore.kernel.org/r/20260131-drm-bridge-alloc-getput-drm_of_find_bridge-4-v2-0-e081bcdc1467@bootlin.com

Changes in v2:
- Removed bouncing recipient: Edmund Dea <edmund.j.dea@intel.com>
- used break instead of a warning patch 3, adapted patch 4 as a
consequence
- Link to v1: https://lore.kernel.org/r/20260116-drm-bridge-alloc-getput-drm_of_find_bridge-4-v1-0-e34b38f50d27@bootlin.com

---
Luca Ceresoli (4):
drm: renesas: rz-du: rzg2l_du_encoder: convert to of_drm_find_and_get_bridge()
drm/kmb/dsi: convert to of_drm_find_and_get_bridge()
drm: rcar-du: encoder: convert to of_drm_find_and_get_bridge()
drm/omap: dss: convert to of_drm_find_and_get_bridge()

drivers/gpu/drm/kmb/kmb_dsi.c | 2 +-
drivers/gpu/drm/omapdrm/dss/output.c | 11 ++++++---
drivers/gpu/drm/renesas/rcar-du/rcar_du_encoder.c | 28 ++++++++++++++++++-----
drivers/gpu/drm/renesas/rcar-du/rcar_du_encoder.h | 1 +
drivers/gpu/drm/renesas/rcar-du/rcar_du_kms.c | 2 ++
drivers/gpu/drm/renesas/rz-du/rzg2l_du_encoder.c | 14 ++++++++----
6 files changed, 44 insertions(+), 14 deletions(-)
---
base-commit: 93eb544f1603103ce6be564bceb36e3875ba7ac0
change-id: 20260107-drm-bridge-alloc-getput-drm_of_find_bridge-4-0a92b361fe9d

Best regards,
--
Luca Ceresoli <luca.ceresoli@bootlin.com>