[PATCH] pmdomain: core: switch to dynamic root device

[PATCH] pmdomain: core: switch to dynamic root device

[Johan Hovold]

Driver core expects devices to be dynamically allocated and will, for
example, complain loudly if a device that lacks a release function is
ever freed.

Use root_device_register() to allocate and register the root device
instead of open coding using a static device.

Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/pmdomain/core.c | 16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/drivers/pmdomain/core.c b/drivers/pmdomain/core.c
index 4d32fc676aaf..e01884f2d7b7 100644
--- a/drivers/pmdomain/core.c
+++ b/drivers/pmdomain/core.c
@@ -33,9 +33,7 @@ static const struct bus_type genpd_provider_bus_type = {
 };
 
 /* The parent for genpd_provider devices. */
-static struct device genpd_provider_bus = {
-	.init_name = "genpd_provider",
-};
+static struct device *genpd_provider_bus;
 
 #define GENPD_RETRY_MAX_MS	250		/* Approximate */
 
@@ -2325,7 +2323,7 @@ static int genpd_alloc_data(struct generic_pm_domain *genpd)
 	device_initialize(&genpd->dev);
 	genpd->dev.release = genpd_provider_release;
 	genpd->dev.bus = &genpd_provider_bus_type;
-	genpd->dev.parent = &genpd_provider_bus;
+	genpd->dev.parent = genpd_provider_bus;
 
 	if (!genpd_is_dev_name_fw(genpd)) {
 		dev_set_name(&genpd->dev, "%s", genpd->name);
@@ -3567,11 +3565,9 @@ static int __init genpd_bus_init(void)
 {
 	int ret;
 
-	ret = device_register(&genpd_provider_bus);
-	if (ret) {
-		put_device(&genpd_provider_bus);
-		return ret;
-	}
+	genpd_provider_bus = root_device_register("genpd_provider");
+	if (IS_ERR(genpd_provider_bus))
+		return PTR_ERR(genpd_provider_bus);
 
 	ret = bus_register(&genpd_provider_bus_type);
 	if (ret)
@@ -3593,7 +3589,7 @@ static int __init genpd_bus_init(void)
 err_prov_bus:
 	bus_unregister(&genpd_provider_bus_type);
 err_dev:
-	device_unregister(&genpd_provider_bus);
+	root_device_unregister(genpd_provider_bus);
 	return ret;
 }
 core_initcall(genpd_bus_init);
-- 
2.53.0

Re: [PATCH] pmdomain: core: switch to dynamic root device

[Ulf Hansson]

On Fri, Apr 24, 2026 at 12:40 PM Johan Hovold <johan@kernel.org> wrote:
>
> Driver core expects devices to be dynamically allocated and will, for
> example, complain loudly if a device that lacks a release function is
> ever freed.
>
> Use root_device_register() to allocate and register the root device
> instead of open coding using a static device.
>
> Signed-off-by: Johan Hovold <johan@kernel.org>

Applied for next, thanks!

Kind regards
Uffe


> ---
>  drivers/pmdomain/core.c | 16 ++++++----------
>  1 file changed, 6 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/pmdomain/core.c b/drivers/pmdomain/core.c
> index 4d32fc676aaf..e01884f2d7b7 100644
> --- a/drivers/pmdomain/core.c
> +++ b/drivers/pmdomain/core.c
> @@ -33,9 +33,7 @@ static const struct bus_type genpd_provider_bus_type = {
>  };
>
>  /* The parent for genpd_provider devices. */
> -static struct device genpd_provider_bus = {
> -       .init_name = "genpd_provider",
> -};
> +static struct device *genpd_provider_bus;
>
>  #define GENPD_RETRY_MAX_MS     250             /* Approximate */
>
> @@ -2325,7 +2323,7 @@ static int genpd_alloc_data(struct generic_pm_domain *genpd)
>         device_initialize(&genpd->dev);
>         genpd->dev.release = genpd_provider_release;
>         genpd->dev.bus = &genpd_provider_bus_type;
> -       genpd->dev.parent = &genpd_provider_bus;
> +       genpd->dev.parent = genpd_provider_bus;
>
>         if (!genpd_is_dev_name_fw(genpd)) {
>                 dev_set_name(&genpd->dev, "%s", genpd->name);
> @@ -3567,11 +3565,9 @@ static int __init genpd_bus_init(void)
>  {
>         int ret;
>
> -       ret = device_register(&genpd_provider_bus);
> -       if (ret) {
> -               put_device(&genpd_provider_bus);
> -               return ret;
> -       }
> +       genpd_provider_bus = root_device_register("genpd_provider");
> +       if (IS_ERR(genpd_provider_bus))
> +               return PTR_ERR(genpd_provider_bus);
>
>         ret = bus_register(&genpd_provider_bus_type);
>         if (ret)
> @@ -3593,7 +3589,7 @@ static int __init genpd_bus_init(void)
>  err_prov_bus:
>         bus_unregister(&genpd_provider_bus_type);
>  err_dev:
> -       device_unregister(&genpd_provider_bus);
> +       root_device_unregister(genpd_provider_bus);
>         return ret;
>  }
>  core_initcall(genpd_bus_init);
> --
> 2.53.0

Re: [PATCH] pmdomain: core: switch to dynamic root device

[Geert Uytterhoeven]

Hi Johan,

On Fri, 24 Apr 2026 at 12:41, Johan Hovold <johan@kernel.org> wrote:
> Driver core expects devices to be dynamically allocated and will, for
> example, complain loudly if a device that lacks a release function is
> ever freed.
>
> Use root_device_register() to allocate and register the root device
> instead of open coding using a static device.
>
> Signed-off-by: Johan Hovold <johan@kernel.org>

Thanks for your patch, which is now commit a96e40f4afdcb52a
("pmdomain: core: switch to dynamic root device") in pmdomain/next.
On e.g. R-Car H1, R-Car M2-W, and R-Car H3, this causes scary messages
when systemd-journald.service is started:

    synth uevent: /always-on: failed to send uevent
    genpd_provider always-on: uevent: failed to send synthetic uevent: -22
    synth uevent: /ca15-cpu0: failed to send uevent
    genpd_provider ca15-cpu0: uevent: failed to send synthetic uevent: -22
    [...]

Reverting the commit fixes the issue.

> --- a/drivers/pmdomain/core.c
> +++ b/drivers/pmdomain/core.c
> @@ -33,9 +33,7 @@ static const struct bus_type genpd_provider_bus_type = {
>  };
>
>  /* The parent for genpd_provider devices. */
> -static struct device genpd_provider_bus = {
> -       .init_name = "genpd_provider",
> -};
> +static struct device *genpd_provider_bus;
>
>  #define GENPD_RETRY_MAX_MS     250             /* Approximate */
>
> @@ -2325,7 +2323,7 @@ static int genpd_alloc_data(struct generic_pm_domain *genpd)
>         device_initialize(&genpd->dev);
>         genpd->dev.release = genpd_provider_release;
>         genpd->dev.bus = &genpd_provider_bus_type;
> -       genpd->dev.parent = &genpd_provider_bus;
> +       genpd->dev.parent = genpd_provider_bus;
>
>         if (!genpd_is_dev_name_fw(genpd)) {
>                 dev_set_name(&genpd->dev, "%s", genpd->name);
> @@ -3567,11 +3565,9 @@ static int __init genpd_bus_init(void)
>  {
>         int ret;
>
> -       ret = device_register(&genpd_provider_bus);
> -       if (ret) {
> -               put_device(&genpd_provider_bus);
> -               return ret;
> -       }
> +       genpd_provider_bus = root_device_register("genpd_provider");
> +       if (IS_ERR(genpd_provider_bus))
> +               return PTR_ERR(genpd_provider_bus);
>
>         ret = bus_register(&genpd_provider_bus_type);
>         if (ret)
> @@ -3593,7 +3589,7 @@ static int __init genpd_bus_init(void)
>  err_prov_bus:
>         bus_unregister(&genpd_provider_bus_type);
>  err_dev:
> -       device_unregister(&genpd_provider_bus);
> +       root_device_unregister(genpd_provider_bus);
>         return ret;
>  }
>  core_initcall(genpd_bus_init);

Apparently this is done too late for drivers/pmdomain/renesas/rcar-sysc.c,
which registers PM domains from an early_initcall().  Doing all work in
rcar-sysc.c from the postcore_initcall() is not an option, as the
CPU power domains are needed for secondary CPU startup on R-Car H1.

Note that R-Car Gen4 is not affected, as it uses rcar-gen4-sysc.c
instead.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@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

Re: [PATCH] pmdomain: core: switch to dynamic root device

[Geert Uytterhoeven]

On Tue, 9 Jun 2026 at 12:53, Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> On Fri, 24 Apr 2026 at 12:41, Johan Hovold <johan@kernel.org> wrote:
> > Driver core expects devices to be dynamically allocated and will, for
> > example, complain loudly if a device that lacks a release function is
> > ever freed.
> >
> > Use root_device_register() to allocate and register the root device
> > instead of open coding using a static device.
> >
> > Signed-off-by: Johan Hovold <johan@kernel.org>
>
> Thanks for your patch, which is now commit a96e40f4afdcb52a
> ("pmdomain: core: switch to dynamic root device") in pmdomain/next.
> On e.g. R-Car H1, R-Car M2-W, and R-Car H3, this causes scary messages
> when systemd-journald.service is started:
>
>     synth uevent: /always-on: failed to send uevent
>     genpd_provider always-on: uevent: failed to send synthetic uevent: -22
>     synth uevent: /ca15-cpu0: failed to send uevent
>     genpd_provider ca15-cpu0: uevent: failed to send synthetic uevent: -22
>     [...]

I missed that there is another set on e.g. R-Car H1 for the clock domain:

    synth uevent: /clocks: failed to send uevent
    genpd_provider clocks: uevent: failed to send synthetic uevent: -22

>
> Reverting the commit fixes the issue.
>
> > --- a/drivers/pmdomain/core.c
> > +++ b/drivers/pmdomain/core.c
> > @@ -33,9 +33,7 @@ static const struct bus_type genpd_provider_bus_type = {
> >  };
> >
> >  /* The parent for genpd_provider devices. */
> > -static struct device genpd_provider_bus = {
> > -       .init_name = "genpd_provider",
> > -};
> > +static struct device *genpd_provider_bus;
> >
> >  #define GENPD_RETRY_MAX_MS     250             /* Approximate */
> >
> > @@ -2325,7 +2323,7 @@ static int genpd_alloc_data(struct generic_pm_domain *genpd)
> >         device_initialize(&genpd->dev);
> >         genpd->dev.release = genpd_provider_release;
> >         genpd->dev.bus = &genpd_provider_bus_type;
> > -       genpd->dev.parent = &genpd_provider_bus;
> > +       genpd->dev.parent = genpd_provider_bus;
> >
> >         if (!genpd_is_dev_name_fw(genpd)) {
> >                 dev_set_name(&genpd->dev, "%s", genpd->name);
> > @@ -3567,11 +3565,9 @@ static int __init genpd_bus_init(void)
> >  {
> >         int ret;
> >
> > -       ret = device_register(&genpd_provider_bus);
> > -       if (ret) {
> > -               put_device(&genpd_provider_bus);
> > -               return ret;
> > -       }
> > +       genpd_provider_bus = root_device_register("genpd_provider");
> > +       if (IS_ERR(genpd_provider_bus))
> > +               return PTR_ERR(genpd_provider_bus);
> >
> >         ret = bus_register(&genpd_provider_bus_type);
> >         if (ret)
> > @@ -3593,7 +3589,7 @@ static int __init genpd_bus_init(void)
> >  err_prov_bus:
> >         bus_unregister(&genpd_provider_bus_type);
> >  err_dev:
> > -       device_unregister(&genpd_provider_bus);
> > +       root_device_unregister(genpd_provider_bus);
> >         return ret;
> >  }
> >  core_initcall(genpd_bus_init);
>
> Apparently this is done too late for drivers/pmdomain/renesas/rcar-sysc.c,
> which registers PM domains from an early_initcall().  Doing all work in
> rcar-sysc.c from the postcore_initcall() is not an option, as the
> CPU power domains are needed for secondary CPU startup on R-Car H1.

Same story for cpg_mstp_add_clk_domain(), which is called from

    CLK_OF_DECLARE(r8a7778_cpg_clks, "renesas,r8a7778-cpg-clocks",
                   r8a7778_cpg_clocks_init);
    CLK_OF_DECLARE(r8a7779_cpg_clks, "renesas,r8a7779-cpg-clocks",
                   r8a7779_cpg_clocks_init);
    CLK_OF_DECLARE(rz_cpg_clks, "renesas,rz-cpg-clocks", rz_cpg_clocks_init);

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@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

Re: [PATCH] pmdomain: core: switch to dynamic root device

[Johan Hovold]

Hi Geert,

On Tue, Jun 09, 2026 at 12:53:59PM +0200, Geert Uytterhoeven wrote:

> On Fri, 24 Apr 2026 at 12:41, Johan Hovold <johan@kernel.org> wrote:
> > Driver core expects devices to be dynamically allocated and will, for
> > example, complain loudly if a device that lacks a release function is
> > ever freed.
> >
> > Use root_device_register() to allocate and register the root device
> > instead of open coding using a static device.
> >
> > Signed-off-by: Johan Hovold <johan@kernel.org>
> 
> Thanks for your patch, which is now commit a96e40f4afdcb52a
> ("pmdomain: core: switch to dynamic root device") in pmdomain/next.
> On e.g. R-Car H1, R-Car M2-W, and R-Car H3, this causes scary messages
> when systemd-journald.service is started:
> 
>     synth uevent: /always-on: failed to send uevent
>     genpd_provider always-on: uevent: failed to send synthetic uevent: -22
>     synth uevent: /ca15-cpu0: failed to send uevent
>     genpd_provider ca15-cpu0: uevent: failed to send synthetic uevent: -22
>     [...]
> 
> Reverting the commit fixes the issue.

Thanks for the report and sorry about the breakage.

I mistakenly convinced myself that this would not be an issue due to the
pmdomain code making sure that the bus has been registered but missed
the two-step initialisation.

I just sent a fix here if you want to give it a spin:

	https://lore.kernel.org/lkml/20260609160634.246526-1-johan@kernel.org/

Johan