Re: [PATCH v3 00/22] drm: convert all bridges to devm_drm_bridge_alloc()

[Luca Ceresoli <luca.ceresoli@bootlin.com>]

Hello Maxime, Shawn, Liu, all,

On Fri, 09 May 2025 15:53:26 +0200
Luca Ceresoli <luca.ceresoli@bootlin.com> wrote:

> devm_drm_bridge_alloc() [0] is the new API to allocate and initialize a DRM
> bridge, and the only one supported from now on. It is the first milestone
> towards removal of bridges from a still existing DRM pipeline without
> use-after-free.

I applied on drm-misc-next patches 3-17,20-21 as they match all the
criteria:
 - At least a Acked-by (or R-by maintainers)
 - patch is for drm-misc

Being my very first commits to drm-misc, I tried to be careful, and
double checked all the patches with Louis (thanks!).

Here are the pending questions and plan for the remaining patches.

>       Revert "drm/exynos: mic: convert to devm_drm_bridge_alloc() API"

This reverts the commit applied my mistake:
https://gitlab.freedesktop.org/drm/misc/kernel/-/commit/91c5c7b5bb2dd09b43b025bce6d790d3c79f4518

Neither the  original patch nor the revert has been reviewed/acked.

As the commit was a mistake, I'm applying the revert by the end of this
week (i.e. on Friday) unless there are better instructions.

>       drm: convert many bridge drivers from devm_kzalloc() to devm_drm_bridge_alloc() API

This patch affects multiple drivers. Running get_maintainers.pl
points at Shawn Guo's repository. After reviewing the MAINTAINERS file,
this looks like due to the 'N:' line in:

ARM/FREESCALE IMX / MXC ARM ARCHITECTURE
M:	Shawn Guo <shawnguo@kernel.org>
M:	Sascha Hauer <s.hauer@pengutronix.de>
R:	Pengutronix Kernel Team <kernel@pengutronix.de>
...
T:	git git://git.kernel.org/pub/scm/linux/kernel/git/shawnguo/linux.git
N:	imx
...

(https://gitlab.freedesktop.org/drm/misc/kernel/-/blob/drm-misc-next/MAINTAINERS?ref_type=heads#L2511-2528)

Here 'imx' matches the 'drivers/gpu/drm/bridge/imx/imx-legacy-bridge.c'
file that is touched by the patch. That regexp appears overly generic to me.

Shawn, can it be fixed by making it less generic?

If not, can we at least add a band-aid 'X:' entry for
drivers/gpu/drm/bridge/imx?

I think the other matching entry is the one to consider:

DRM DRIVERS FOR FREESCALE IMX BRIDGE
M:	Liu Ying <victor.liu@nxp.com>
L:	dri-devel@lists.freedesktop.org
S:	Maintained
F:	Documentation/devicetree/bindings/display/bridge/fsl,imx8qxp-ldb.yaml
F:	Documentation/devicetree/bindings/display/bridge/fsl,imx8qxp-pixel-combiner.yaml
F:	Documentation/devicetree/bindings/display/bridge/fsl,imx8qxp-pixel-link.yaml
F:	Documentation/devicetree/bindings/display/bridge/fsl,imx8qxp-pxl2dpi.yaml
F:	drivers/gpu/drm/bridge/imx/

(https://gitlab.freedesktop.org/drm/misc/kernel/-/blob/drm-misc-next/MAINTAINERS?ref_type=heads#L7940-7948)

However it does not list any trees. I _guess_ drm-misc applies here as
a fallback as well as common sense.

Liu, should this entry have a 'T:' line for drm/misc?

>       drm/bridge: imx8qxp-pixel-combiner: convert to devm_drm_bridge_alloc() API

Not acked/reviewed, some discussion happened. I am resending it in v4,
possibly with updates based on the discussion.

But it has the same issue discussed above, with get_maintiners.pl
pointing at Shawn Guo's tree, so in the future I'm assuming this goes
to drm-misc unless there are news about that.

>       drm/bridge: tc358767: convert to devm_drm_bridge_alloc() API

No feedback, resending in v4.

>       drm/todo: add entry to remove devm_drm_put_bridge()

This involves documentation maintained on another tree. Where should it
be applied? There are two matching entries in MAINTAINERS:

 * DRM DRIVERS -> the drm tree
 * DRM DRIVERS AND MISC GPU PATCHES -> the drm-misc tree

To me it looks like the second is obviously the closest match as we are
dealing with DRM bridges, so I'm applying this as well on Friday unless
there are better instructions.

Best regards,
Luca

-- 
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com