Hi Marek, Maxime,
On Mon, 7 Jul 2025 12:12:51 +0200
Marek Szyprowski <m.szyprow...@samsung.com> wrote:
> On 07.07.2025 11:21, Maxime Ripard wrote:
> > On Thu, Jul 03, 2025 at 05:50:32PM +0200, Luca Ceresoli wrote:
> >> On Tue, 1 Jul 2025 16:27:54 +0200
> >> Maxime Ripard <mrip...@kernel.org> wrote:
> >>
> >>> On Tue, Jul 01, 2025 at 04:02:19PM +0200, Luca Ceresoli wrote:
> >>>> Hello Marek, Maxime,
> >>>>
> >>>> thanks Marek for spotting the issue and sending a patch!
> >>>>
> >>>> On Mon, 30 Jun 2025 18:44:24 +0200
> >>>> Maxime Ripard <mrip...@kernel.org> wrote:
> >>>>
> >>>>>> @@ -1643,7 +1625,7 @@ int analogix_dp_bind(struct analogix_dp_device
> >>>>>> *dp, struct drm_device *drm_dev)
> >>>>>> return ret;
> >>>>>> }
> >>>>>>
> >>>>>> - ret = analogix_dp_create_bridge(drm_dev, dp);
> >>>>>> + ret = drm_bridge_attach(dp->encoder, &dp->bridge, NULL, 0);
> >>>>>> if (ret) {
> >>>>>> DRM_ERROR("failed to create bridge (%d)\n", ret);
> >>>>>> goto err_unregister_aux;
> >>>>> It looks like you don't set bridge->driver_private anymore. Is it on
> >>>>> purpose?
> >>>> This looks correct to me. In current code, driver_private is used to
> >>>> hold a pointer to the driver private struct (struct
> >>>> analogix_dp_device). With devm_drm_bridge_alloc() container_of() is now
> >>>> enough, no pointer is needed. With the patch applied, driver_private
> >>>> becomes unused.
> >>> Then we should remove it from the structure if it's unused.
> >> Makes sense now that struct drm_bridge is meant to be always embedded
> >> in a driver-private struct. But several drivers are still using it, so
> >> those would need to be updated beforehand:
> >>
> >> $ git grep -l driver_private -- drivers/gpu/drm/ | wc -l
> >> 23
> >> $
> > Ah, you're right, sorry for the noise.
> >
> >> So I think this patch should be taken as it fixes a regression. Do you
> >> agree on this?
> > As far as I know, that commit only exists in drm-misc-next. Also, it
> > should have a Fixes tag.
>
> I wasn't sure which commit should be listed as Fixes tag in this case.
> The mentioned 9c399719cfb9 ("drm: convert many bridge drivers from
> devm_kzalloc() to devm_drm_bridge_alloc() API")?
Despite being somewhat orthogonal, I think it should be commit
a7748dd127ea ("drm/bridge: get/put the bridge reference in
drm_bridge_add/remove()") just because it is the very first commit in
the drm-misc-next history introducing a get/put pair, and thus
triggering the refcount warning.
I'm applying with that added.
Thanks both for the discussion.
Luca
--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
