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. Where applicable 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:
- Part 2: mostly drivers in drivers/gpu/drm/bridge [2]
- Part 3: other drivers, low-medium complexity [this series]
- Part 4: other drivers, complex (not sent yet)
[2] https://lore.kernel.org/all/20260107-drm-bridge-alloc-getput-drm_of_find_bridge-2-v1-0-283d7bba061a@bootlin.com/
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
---
Changes in v2:
- Patch 3: fix missing drm_bridge_put()
- Link to v1: https://lore.kernel.org/r/20260107-drm-bridge-alloc-getput-drm_of_find_bridge-3-v1-0-ef48a517828e@bootlin.com
---
Luca Ceresoli (6):
drm/bridge: dw-hdmi: convert to of_drm_find_and_get_bridge()
drm/meson/dw-hdmi: convert to of_drm_find_and_get_bridge()
drm/imx/dw-hdmi: convert to of_drm_find_and_get_bridge()
drm/mediatek: mtk_hdmi*: convert to of_drm_find_and_get_bridge()
drm/exynos: hdmi: convert to of_drm_find_and_get_bridge()
drm: rcar-du: lvds: convert to of_drm_find_and_get_bridge()
drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 7 +++----
drivers/gpu/drm/exynos/exynos_hdmi.c | 4 +++-
drivers/gpu/drm/imx/ipuv3/dw_hdmi-imx.c | 7 +++++--
drivers/gpu/drm/mediatek/mtk_hdmi.c | 4 ++--
drivers/gpu/drm/mediatek/mtk_hdmi_common.c | 4 ++--
drivers/gpu/drm/mediatek/mtk_hdmi_common.h | 1 -
drivers/gpu/drm/mediatek/mtk_hdmi_v2.c | 4 ++--
drivers/gpu/drm/meson/meson_dw_hdmi.c | 6 +++++-
drivers/gpu/drm/renesas/rcar-du/rcar_lvds.c | 10 +++++++++-
9 files changed, 31 insertions(+), 16 deletions(-)
---
base-commit: 13450a1f72fd24c405626c881ae7c9ce5f0d2a28
change-id: 20260107-drm-bridge-alloc-getput-drm_of_find_bridge-3-4f997ea7c79f
Best regards,
--
Luca Ceresoli <luca.ceresoli@bootlin.com>