Message-Id: <20260109-drm-bridge-alloc-getput-drm_of_find_bridge-3-v2-0-8d7a3dbacdf4@bootlin.com>
Date: Fri, 09 Jan 2026 11:02:49 +0100
From: Luca Ceresoli <luca.ceresoli@...tlin.com>
To: Andrzej Hajda <andrzej.hajda@...el.com>, 
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Cc: Marek Szyprowski <m.szyprowski@...sung.com>, 
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 Luca Ceresoli <luca.ceresoli@...tlin.com>
Subject: [PATCH v2 0/6] drm/bridge: convert users of of_drm_find_bridge(),
 part 3

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@...tlin.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@...tlin.com>

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