Re: [PATCH v6 15/26] drm/bridge: devm_drm_of_get_bridge and drmm_of_get_bridge: automatically put the bridge

Dmitry Baryshkov
2025-02-07T20:30:07Z

On Fri, Feb 07, 2025 at 11:44:01AM +0100, Luca Ceresoli wrote:
> On Fri, 7 Feb 2025 05:17:43 +0200
> Dmitry Baryshkov <dmitry.baryshkov@linaro.org> wrote:
>
> > On Thu, Feb 06, 2025 at 07:14:30PM +0100, Luca Ceresoli wrote:
> > > Add a devm/drmm action to these functions so the bridge reference is
> > > dropped automatically when the caller is removed.
> >
> > I think the get() should go to the underlying of_drm_bridge_find() function.
>
> It is done in the following patch.
>
> Indeed I could swap patches 15 and 16 for clarity. Or I could squash
> together patches 14+15+16, as they are various parts or the refcounted
> bridge implementation, but I felt like keeping them separated would
> help reviewing.

I think most of refcounting should be introduced as a single patch,
otherwise you risk having memory leaks or disappearing bridges.

>
> > Also it really feels like it's an overkill to keep the wrappers. After
> > getting bridge being handled by the panel code would it be possible to
> > drop all of them?
>
> Do you mean having only drm_of_get_bridge_by_node(), without any devm
> or drmm variant? I'm not sure it is a good idea. Most DRM code (well,
> all of it, technically) is currently unable of working with refcounted
> bridges, but if they use the devm variant they will put the ref when
> they disappear.
>
> > Then this patch might introduce one new devm_
> > function? Or are drmm_ functions actually being used to store data in
> > the drmm-managed memory?
>
> Which devm function are you thinking about? Sorry, I'm not following
> here.

drmm_of_get_bridge() / devm_of_get_bridge(). I have a feeling (which of
course might be wrong), that they were used somewhat randomly in some
cases.

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

--
With best wishes
Dmitry