[PATCH v4 5/8] pmdomain: Make genpd_get_from_provider() return -EPROBE_DEFER

[Geert Uytterhoeven]

Hi Laurent,

On Mon, 19 Oct 2026 at 18:05, Laurent Pinchart
<laurent.pinchart at ideasonboard.com> wrote:
> On Fri, Oct 16, 2026 at 05:55:44PM +0200, Geert Uytterhoeven wrote:
> > Unlike provider-based look-up functions in other subsystems[1],
> > genpd_get_from_provider() returns -ENOENT instead of -EPROBE_DEFER when
> > the provider is not found, thus not supporting probe deferral.
> > Currently this is worked around in of_genpd_add_subdomain() by remapping
> > -ENOENT[2].
>
> But not in the other functions calling genpd_get_from_provider() and
> propagating the error up. Have you validated that no existing call
> stacks will break ?
>
> > Fix this for all current and future callers by returning -EPROBE_DEFER
> > instead, and drop the no longer needed remapping code.
> >
> > [1] of_clk_get_hw_from_clkspec(), __fwnode_reset_control_get()),
> > [2] Commit 18027d6f392ee8d8 ("PM: domains: Make of_genpd_add_subdomain()
> >     return -EPROBE_DEFER").
> >
> > Signed-off-by: Geert Uytterhoeven <geert+renesas at glider.be>
> > ---
> > v4:
> >   - New.
> > ---
> >  drivers/pmdomain/core.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/pmdomain/core.c b/drivers/pmdomain/core.c
> > index 964e44c2f78f1d55..88c886814a5b9da3 100644
> > --- a/drivers/pmdomain/core.c
> > +++ b/drivers/pmdomain/core.c
> > @@ -3021,7 +3021,7 @@ EXPORT_SYMBOL_GPL(of_genpd_del_provider);
> >  static struct generic_pm_domain *genpd_get_from_provider(
> >                                       const struct of_phandle_args *genpdspec)
> >  {
> > -     struct generic_pm_domain *genpd = ERR_PTR(-ENOENT);
> > +     struct generic_pm_domain *genpd = ERR_PTR(-EPROBE_DEFER);
> >       struct of_genpd_provider *provider;
> >
> >       if (!genpdspec)
>
> Expanding the context:
>
> >               return ERR_PTR(-EINVAL);
> >
> >       mutex_lock(&of_genpd_mutex);
> >
> >       /* Check if we have such a provider in our array */
> >       list_for_each_entry(provider, &of_genpd_providers, link) {
> >               if (provider->node == genpdspec->np)
> >                       genpd = provider->xlate(genpdspec, provider->data);
> >               if (!IS_ERR(genpd))
> >                       break;
> >       }
> >
> >       mutex_unlock(&of_genpd_mutex);
> >
> >       return genpd;
>
> The for loop seems to imply that we can have multiple providers for the
> same node. In case a provider fails, the function overrides the error
> code from -EPROBE_DEFER to whatever the first xlate() returns. That may
> cause issues for your use case.

The code has been like that since its introduction.  Technically one
can register multiple providers for the same device node, but one
can never safely remove one of them, as of_genpd_del_provider() just
considers the device node, and removes the first matching provider.
So I think someone just didn't like nesting curly braces, and tried
to be smart ;-)

> If the of_genpd_providers list doesn't expect multiple providers per
> device node, I would change the above into
>
>         list_for_each_entry(provider, &of_genpd_providers, link) {
>                 if (provider->node == genpdspec->np) {
>                         genpd = provider->xlate(genpdspec, provider->data);
>                         break;
>                 }
>         }
>
> to make it explicit.

Will do.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds