Hi Thierry,
> -----Original Message-----
> From: Thierry Reding <thierry.red...@gmail.com>
> Sent: 07 May 2025 17:00
> To: Biju Das <biju.das...@bp.renesas.com>
> Subject: Re: [PATCH] drm/tegra: rgb: Fix the unbound reference count
>
> On Wed, Feb 05, 2025 at 11:21:35AM +0000, Biju Das wrote:
> > The of_get_child_by_name() increments the refcount in
> > tegra_dc_rgb_probe, but the driver does not decrement the refcount
> > during unbind. Fix the unbound reference count using
> > devm_add_action_or_reset() helper.
> >
> > Fixes: d8f4a9eda006 ("drm: Add NVIDIA Tegra20 support")
> > Signed-off-by: Biju Das <biju.das...@bp.renesas.com>
> > ---
> > drivers/gpu/drm/tegra/rgb.c | 14 +++++++++++++-
> > 1 file changed, 13 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/tegra/rgb.c b/drivers/gpu/drm/tegra/rgb.c
> > index 1e8ec50b759e..2065157daab3 100644
> > --- a/drivers/gpu/drm/tegra/rgb.c
> > +++ b/drivers/gpu/drm/tegra/rgb.c
> > @@ -200,6 +200,11 @@ static const struct drm_encoder_helper_funcs
> > tegra_rgb_encoder_helper_funcs = {
> > .atomic_check = tegra_rgb_encoder_atomic_check, };
> >
> > +static void tegra_dc_of_node_put(void *data) {
> > + of_node_put(data);
> > +}
> > +
> > int tegra_dc_rgb_probe(struct tegra_dc *dc) {
> > struct device_node *np;
> > @@ -207,7 +212,14 @@ int tegra_dc_rgb_probe(struct tegra_dc *dc)
> > int err;
> >
> > np = of_get_child_by_name(dc->dev->of_node, "rgb");
> > - if (!np || !of_device_is_available(np))
> > + if (!np)
> > + return -ENODEV;
> > +
> > + err = devm_add_action_or_reset(dc->dev, tegra_dc_of_node_put,
> > +dc->dev);
>
> Actually, I think this needs to be:
>
> err = devm_add_action_or_reset(dc->dev, tegra_dc_of_node_put, np);
>
> otherwise tegra_dc_of_node_put() would attempt to call of_node_put() on
> dc->dev, which won't work, or rather cause corruption of some sort.
>
> Shout if you disagree.
I agree, is it something you can do while applying or you want me to send v2?
Please let me know.
Cheers,
Biju
