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(-)
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-v6-0-9d6f2c9c3058@bootlin.com/t/#u
Signed-off-by: Luca Ceresoli <luca.ceresoli@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-v1-0-48920b9cf369@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(-)
---
base-commit: b13c47e0f6f5a7be56ed93d596f80eb9d8e12c77
change-id: 20250709-drm-bridge-alloc-getput-drm_bridge_get_next_bridge-1df6aaf62136
Best regards,
--
Luca Ceresoli <luca.ceresoli@bootlin.com>
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-v6-0-9d6f2c9c3058@bootlin.com/t/#u
>
> Signed-off-by: Luca Ceresoli <luca.ceresoli@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-v1-0-48920b9cf369@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)) {
> ---
> base-commit: b13c47e0f6f5a7be56ed93d596f80eb9d8e12c77
> change-id: 20250709-drm-bridge-alloc-getput-drm_bridge_get_next_bridge-1df6aaf62136
>
> Best regards,
--
Regards,
Liu Ying
Hello Liu,
thanks for having reviewed this series.
On Mon, 4 Aug 2025 12:02:48 +0800
Liu Ying <victor.liu@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-v6-0-9d6f2c9c3058@bootlin.com/t/#u
> >
> > Signed-off-by: Luca Ceresoli <luca.ceresoli@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-v1-0-48920b9cf369@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-be8f4ae006e9@bootlin.com/
Luca
--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
On Fri, 01 Aug 2025 19:05:22 +0200, 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().
>
> [...]
Applied, thanks!
[1/9] list: add list_last_entry_or_null()
commit: cb86408b1fc2e3f6fe45ebe8509a5404060e01e0
[2/9] drm/bridge: add drm_bridge_chain_get_last_bridge()
commit: d77ad5178e90f5aa4ce6085510b3b2f742abc5f0
[3/9] drm/bridge: imx93-mipi-dsi: use drm_bridge_chain_get_last_bridge()
commit: 5849eff7f06709c98baa7989806165fe30bd0cbe
[4/9] drm/omapdrm: use drm_bridge_chain_get_last_bridge()
commit: c3183f71c3f1f004a0ca0b84c45c40d8b84dce3d
[5/9] drm/bridge: add drm_bridge_is_last()
commit: e4cedfd4f0fc839bb3c783d7e827e9755e1af5cf
[6/9] drm/display: bridge_connector: use drm_bridge_is_last()
commit: 306734a1c76ce35fa613ea823a31ddbcdbf1eef5
Best regards,
--
Luca Ceresoli <luca.ceresoli@bootlin.com>
Hello, On Tue, 02 Sep 2025 15:25:31 +0200 Luca Ceresoli <luca.ceresoli@bootlin.com> wrote: > On Fri, 01 Aug 2025 19:05:22 +0200, 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(). > > > > [...] > > Applied, thanks! > > [1/9] list: add list_last_entry_or_null() > commit: cb86408b1fc2e3f6fe45ebe8509a5404060e01e0 > [2/9] drm/bridge: add drm_bridge_chain_get_last_bridge() > commit: d77ad5178e90f5aa4ce6085510b3b2f742abc5f0 > [3/9] drm/bridge: imx93-mipi-dsi: use drm_bridge_chain_get_last_bridge() > commit: 5849eff7f06709c98baa7989806165fe30bd0cbe > [4/9] drm/omapdrm: use drm_bridge_chain_get_last_bridge() > commit: c3183f71c3f1f004a0ca0b84c45c40d8b84dce3d > [5/9] drm/bridge: add drm_bridge_is_last() > commit: e4cedfd4f0fc839bb3c783d7e827e9755e1af5cf > [6/9] drm/display: bridge_connector: use drm_bridge_is_last() > commit: 306734a1c76ce35fa613ea823a31ddbcdbf1eef5 Last 3 patches applied (but I don't get why 'b4 ty' fails at finding them to send an automated thank-you e-mail). Luca -- Luca Ceresoli, Bootlin Embedded Linux and Kernel engineering https://bootlin.com
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