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@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. 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_bridge-2-v1-0-283d7bba061a@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 | 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,
--
Luca Ceresoli <luca.ceresoli@bootlin.com>