Hello Liu, thanks for having reviewed this series.
On Mon, 4 Aug 2025 12:02:48 +0800 Liu Ying <victor....@nxp.com> wrote: > Hi Luca, > > On 08/01/2025, Luca Ceresoli wrote: > > Note: the cover in v1 was mentioning by mistake > > drm_bridge_get_last_bridge() instead of drm_bridge_get_next_bridge(). > > ^^^^ > > > > This series adds drm_bridge_get/put() calls for DRM bridges returned by > > drm_bridge_get_next_bridge(). > > > > This is part of the work towards removal of bridges from a still existing > > DRM pipeline without use-after-free. The grand plan was discussed in [1]. > > Here's the work breakdown (➜ marks the current series): > > > > 1. ➜ add refcounting to DRM bridges (struct drm_bridge) > > (based on devm_drm_bridge_alloc() [0]) > > A. ✔ add new alloc API and refcounting (in v6.16-rc1) > > B. ✔ convert all bridge drivers to new API (now in drm-misc-next) > > C. ✔ kunit tests (now in drm-misc-next) > > D. ✔ add get/put to drm_bridge_add/remove() + attach/detach() > > and warn on old allocation pattern (now in drm-misc-next) > > E. ➜ add get/put on drm_bridge accessors > > 1. ✔ drm_bridge_chain_get_first_bridge() + add a cleanup action > > 2. ✔ drm_bridge_get_prev_bridge() > > 3. ➜ drm_bridge_get_next_bridge() > > 4. … drm_for_each_bridge_in_chain() > > 5. drm_bridge_connector_init > > 6. of_drm_find_bridge > > 7. drm_of_find_panel_or_bridge, *_of_get_bridge > > F. debugfs improvements > > 2. handle gracefully atomic updates during bridge removal > > 3. … avoid DSI host drivers to have dangling pointers to DSI devices > > 4. finish the hotplug bridge work, removing the "always-disconnected" > > connector, moving code to the core and potentially removing the > > hotplug-bridge itself (this needs to be clarified as points 1-3 are > > developed) > > > > There are various users of drm_bridge_get_next_bridge() which cannot be > > converted easily. Luckily they are not really looking for the next bridge, > > but for something else, such as getting the last bridge in the encoder > > chain or checking whether a bridge is the last in the encoder chain. So > > introduce better functions for those users and use them instead of > > drm_bridge_get_next_bridge(), making the code cleaner at the same time. > > > > Finally add a drm_bridge_get() to drm_bridge_get_next_bridge() and > > drm_bridge_put() to the remaining, and legitimate, calls. > > > > [0] > > https://gitlab.freedesktop.org/drm/misc/kernel/-/commit/0cc6aadd7fc1e629b715ea3d1ba537ef2da95eec > > [1] > > https://lore.kernel.org/lkml/20250206-hotplug-drm-bridge-v6-0-9d6f2c9c3...@bootlin.com/t/#u > > > > Signed-off-by: Luca Ceresoli <luca.ceres...@bootlin.com> > > --- > > Changes in v2: > > - Use cleanup action in patches 4, 8 and 9 > > - Fix: replace get_last -> get_next in cover > > - Link to v1: > > https://lore.kernel.org/r/20250709-drm-bridge-alloc-getput-drm_bridge_get_next_bridge-v1-0-48920b9cf...@bootlin.com > > > > --- > > Luca Ceresoli (9): > > list: add list_last_entry_or_null() > > drm/bridge: add drm_bridge_chain_get_last_bridge() > > drm/bridge: imx93-mipi-dsi: use drm_bridge_chain_get_last_bridge() > > drm/omapdrm: use drm_bridge_chain_get_last_bridge() > > drm/bridge: add drm_bridge_is_last() > > drm/display: bridge_connector: use drm_bridge_is_last() > > drm/bridge: get the bridge returned by drm_bridge_get_next_bridge() > > drm/bridge: put the bridge returned by drm_bridge_get_next_bridge() > > drm/imx: parallel-display: put the bridge returned by > > drm_bridge_get_next_bridge() > > > > drivers/gpu/drm/bridge/imx/imx93-mipi-dsi.c | 12 ++++------ > > drivers/gpu/drm/display/drm_bridge_connector.c | 5 ++-- > > drivers/gpu/drm/drm_bridge.c | 3 +-- > > drivers/gpu/drm/imx/ipuv3/parallel-display.c | 4 ++-- > > drivers/gpu/drm/omapdrm/omap_drv.c | 6 ++--- > > include/drm/drm_bridge.h | 32 > > +++++++++++++++++++++++++- > > include/linux/list.h | 14 +++++++++++ > > 7 files changed, 57 insertions(+), 19 deletions(-) > > Looks like this one needs to be handled by this patch series? > > drivers/gpu/drm/omapdrm/omap_encoder.c:101: > bridge = drm_bridge_get_next_bridge(bridge)) { This is handled in a better way in a separate series, converting the for_each loops around the bridges in an encoder chain: https://lore.kernel.org/all/20250723-drm-bridge-alloc-getput-for_each_bridge-v1-9-be8f4ae00...@bootlin.com/ Luca -- Luca Ceresoli, Bootlin Embedded Linux and Kernel engineering https://bootlin.com
