Re: [PATCH 2/4] drm/bridge: display-connector: Fix I2C adapter resource leak

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

On Fri, Jul 17, 2026 at 05:21:11PM +0200, Luca Ceresoli wrote:
> On Fri Jul 17, 2026 at 5:03 PM CEST, Johan Hovold wrote:
> > On Mon, Jul 06, 2026 at 12:35:40AM +0300, Laurent Pinchart wrote:
> >> If the probe function returns an error after getting the I2C adapter for
> >> DDC, the reference to the adapter is never released. Fix it by releasing
> >> it in the bridge .destroy() handler.
> >>
> >> There is no need to test the ddc pointer with !IS_ERR(), as
> >> of_get_i2c_adapter_by_node() returns NULL on error.
> >
> > I stumbled over this this morning as well and posted a fix here (which
> > releases the adapter on driver unbind as is currently done):
> >
> > 	https://lore.kernel.org/lkml/20260717085716.1619275-1-johan@kernel.org/
> >
> >> Fixes: 6de79dd3a920 ("drm/bridge: display-connector: add ddc-en gpio support")
> >
> > I believe this issue was first introduced by commit 2e2bf3a5584d
> > ("drm/bridge: display-connector: add DP support") a few releases
> > earlier.
> >
> >> Cc: stable@vger.kernel.org
> >> Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
> >
> > Reviewed-by: Johan Hovold <johan@kernel.org>
> 
> While Johan's patch has the benefit of putting the i2c adapter at remove
> time (as opposed to destroy time, which is potentially a long time later),
> it is also more complex. So I'd say this patch is fine.

In this case putting the I2C adapter early is probably fine, but in
general I really prefer reference-counting and releasing references at
destroy time. This ensures that the resources stay available if they
need to be accessed between .remove() and destruction (for instance in a
.release() handler following a close() or munmap() from userspace). I
think late release should be the default, as it's safer, and early
release should be carefully reviewed when it's required.

> Maybe we should have a devm version of of_get_i2c_adapter_by_node() to make
> it all simpler.
> 
> Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com>

-- 
Regards,

Laurent Pinchart