RE: [PATCH v2 08/11] drm/bridge: adv7511: switch to of_drm_get_bridge_by_endpoint()

Biju Das
2026-04-28T11:58:56Z

Hi all,

> -----Original Message-----
> From: dri-devel <dri-devel-bounces@lists.freedesktop.org> On Behalf Of Biju Das
> Sent: 28 April 2026 12:50
> Subject: RE: [PATCH v2 08/11] drm/bridge: adv7511: switch to of_drm_get_bridge_by_endpoint()
>
>
> Hi,
>
> Thanks for the patch.
>
> > -----Original Message-----
> > From: dri-devel <dri-devel-bounces@lists.freedesktop.org> On Behalf Of
> > Luca Ceresoli
> > Sent: 28 April 2026 10:16
> > Subject: [PATCH v2 08/11] drm/bridge: adv7511: switch to
> > of_drm_get_bridge_by_endpoint()
> >
> > This driver calls drm_of_find_panel_or_bridge() with a NULL pointer in
> > the @panel parameter, thus using a reduced feature set of that function.
> > Replace this call with the simpler of_drm_get_bridge_by_endpoint().
> >
> > Since of_drm_get_bridge_by_endpoint() increases the refcount of the
> > returned bridge, ensure it is put on removal. To achieve this, instead
> > of adding an explicit drm_bridge_put(), migrate to the bridge::next_bridge pointer which is
> automatically put when the bridge is eventually freed.
> >
> > Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
> > ---
> > drivers/gpu/drm/bridge/adv7511/adv7511.h | 1 -
> > drivers/gpu/drm/bridge/adv7511/adv7511_drv.c | 11 +++++------
> > 2 files changed, 5 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511.h
> > b/drivers/gpu/drm/bridge/adv7511/adv7511.h
> > index 8be7266fd4f4..12c95198d9a4 100644
> > --- a/drivers/gpu/drm/bridge/adv7511/adv7511.h
> > +++ b/drivers/gpu/drm/bridge/adv7511/adv7511.h
> > @@ -354,7 +354,6 @@ struct adv7511 {
> > enum drm_connector_status status;
> > bool powered;
> >
> > - struct drm_bridge *next_bridge;
> > struct drm_display_mode curr_mode;
> >
> > unsigned int f_tmds;
> > diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> > b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> > index 6bd76c1fb007..498e38579a0f 100644
> > --- a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> > +++ b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> > @@ -851,8 +851,8 @@ static int adv7511_bridge_attach(struct drm_bridge *bridge,
> > struct adv7511 *adv = bridge_to_adv7511(bridge);
> > int ret = 0;
> >
> > - if (adv->next_bridge) {
> > - ret = drm_bridge_attach(encoder, adv->next_bridge, bridge,
> > + if (adv->bridge.next_bridge) {
> > + ret = drm_bridge_attach(encoder, adv->bridge.next_bridge, bridge,
> > flags | DRM_BRIDGE_ATTACH_NO_CONNECTOR);
> > if (ret)
> > return ret;
> > @@ -1251,10 +1251,9 @@ static int adv7511_probe(struct i2c_client
> > *i2c)
> >
> > memset(&link_config, 0, sizeof(link_config));
> >
> > - ret = drm_of_find_panel_or_bridge(dev->of_node, 1, -1, NULL,
> > - &adv7511->next_bridge);
> > - if (ret && ret != -ENODEV)
> > - return ret;
> > + adv7511->bridge.next_bridge = of_drm_get_bridge_by_endpoint(dev->of_node, 1, -1);
> > + if (IS_ERR(adv7511->bridge.next_bridge) && PTR_ERR(adv7511->bridge.next_bridge) != -ENODEV)
> > + return PTR_ERR(adv7511->bridge.next_bridge);
>
> Does it crash, if the error is -EPROBE_DEFER?

I see a crash with patch [1], which is fixed by avoiding the direct assignment.

[1] https://lore.kernel.org/linux-renesas-soc/20260421172910.218497-4-biju.das.jz@bp.renesas.com/

+ next_bridge = devm_drm_of_get_bridge(dev, dev->of_node, 1, 0);
+ if (IS_ERR(next_bridge))
+ return dev_err_probe(dev, PTR_ERR(next_bridge),
+ "failed to get next bridge\n");
+
+ lvds->bridge.next_bridge = next_bridge;

Cheers,
Biju