drivers/pmdomain/core.c | 20 +++++++++++++++++--- 1 file changed, 17 insertions(+), 3 deletions(-)
Since the introduction of the sync_state mechanism, the
"pd_ignore_unused" kernel command line option doesn't really work
anymore. While genpd_power_off_unused() still checks for that flag
before powering down unused domains, the new sync_state callbacks lack
such checks, thus powering down unused domains regardless.
Fix this by adding checks to the sync_state helpers and callbacks.
Factor out the printing of the warning message, to make sure it is
printed only once.
Fixes: 002ebddd695a5399 ("pmdomain: core: Restore behaviour for disabling unused PM domains")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
RFC as I have no need for this in upstream.
---
drivers/pmdomain/core.c | 20 +++++++++++++++++---
1 file changed, 17 insertions(+), 3 deletions(-)
diff --git a/drivers/pmdomain/core.c b/drivers/pmdomain/core.c
index 7b563757935071dd..1f7d90bcc30d12e5 100644
--- a/drivers/pmdomain/core.c
+++ b/drivers/pmdomain/core.c
@@ -1366,6 +1366,16 @@ static int __init pd_ignore_unused_setup(char *__unused)
}
__setup("pd_ignore_unused", pd_ignore_unused_setup);
+static bool genpd_ignore_unused(void)
+{
+ if (pd_ignore_unused) {
+ pr_warn_once("genpd: Not disabling unused power domains\n");
+ return true;
+ }
+
+ return false;
+}
+
/**
* genpd_power_off_unused - Power off all PM domains with no devices in use.
*/
@@ -1373,10 +1383,8 @@ static int __init genpd_power_off_unused(void)
{
struct generic_pm_domain *genpd;
- if (pd_ignore_unused) {
- pr_warn("genpd: Not disabling unused power domains\n");
+ if (genpd_ignore_unused())
return 0;
- }
pr_info("genpd: Disabling unused power domains\n");
mutex_lock(&gpd_list_lock);
@@ -3510,6 +3518,9 @@ void of_genpd_sync_state(struct device_node *np)
{
struct generic_pm_domain *genpd;
+ if (genpd_ignore_unused())
+ return;
+
if (!np)
return;
@@ -3544,6 +3555,9 @@ static void genpd_provider_sync_state(struct device *dev)
break;
case GENPD_SYNC_STATE_SIMPLE:
+ if (genpd_ignore_unused())
+ return;
+
genpd_lock(genpd);
genpd->stay_on = false;
genpd_power_off(genpd, false, 0);
--
2.43.0On Mon, 16 Feb 2026 at 19:47, Geert Uytterhoeven
<geert+renesas@glider.be> wrote:
>
> Since the introduction of the sync_state mechanism, the
> "pd_ignore_unused" kernel command line option doesn't really work
> anymore. While genpd_power_off_unused() still checks for that flag
> before powering down unused domains, the new sync_state callbacks lack
> such checks, thus powering down unused domains regardless.
>
> Fix this by adding checks to the sync_state helpers and callbacks.
> Factor out the printing of the warning message, to make sure it is
> printed only once.
>
> Fixes: 002ebddd695a5399 ("pmdomain: core: Restore behaviour for disabling unused PM domains")
> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
> ---
> RFC as I have no need for this in upstream.
I am trying to understand the use case and whether we should consider
to land this upstream.
Would you mind elaborating on how this is useful for you?
Kind regards
Uffe
> ---
> drivers/pmdomain/core.c | 20 +++++++++++++++++---
> 1 file changed, 17 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/pmdomain/core.c b/drivers/pmdomain/core.c
> index 7b563757935071dd..1f7d90bcc30d12e5 100644
> --- a/drivers/pmdomain/core.c
> +++ b/drivers/pmdomain/core.c
> @@ -1366,6 +1366,16 @@ static int __init pd_ignore_unused_setup(char *__unused)
> }
> __setup("pd_ignore_unused", pd_ignore_unused_setup);
>
> +static bool genpd_ignore_unused(void)
> +{
> + if (pd_ignore_unused) {
> + pr_warn_once("genpd: Not disabling unused power domains\n");
> + return true;
> + }
> +
> + return false;
> +}
> +
> /**
> * genpd_power_off_unused - Power off all PM domains with no devices in use.
> */
> @@ -1373,10 +1383,8 @@ static int __init genpd_power_off_unused(void)
> {
> struct generic_pm_domain *genpd;
>
> - if (pd_ignore_unused) {
> - pr_warn("genpd: Not disabling unused power domains\n");
> + if (genpd_ignore_unused())
> return 0;
> - }
>
> pr_info("genpd: Disabling unused power domains\n");
> mutex_lock(&gpd_list_lock);
> @@ -3510,6 +3518,9 @@ void of_genpd_sync_state(struct device_node *np)
> {
> struct generic_pm_domain *genpd;
>
> + if (genpd_ignore_unused())
> + return;
> +
> if (!np)
> return;
>
> @@ -3544,6 +3555,9 @@ static void genpd_provider_sync_state(struct device *dev)
> break;
>
> case GENPD_SYNC_STATE_SIMPLE:
> + if (genpd_ignore_unused())
> + return;
> +
> genpd_lock(genpd);
> genpd->stay_on = false;
> genpd_power_off(genpd, false, 0);
> --
> 2.43.0
>
Hi Ulf,
On Wed, 4 Mar 2026 at 11:56, Ulf Hansson <ulf.hansson@linaro.org> wrote:
> On Mon, 16 Feb 2026 at 19:47, Geert Uytterhoeven
> <geert+renesas@glider.be> wrote:
> > Since the introduction of the sync_state mechanism, the
> > "pd_ignore_unused" kernel command line option doesn't really work
> > anymore. While genpd_power_off_unused() still checks for that flag
> > before powering down unused domains, the new sync_state callbacks lack
> > such checks, thus powering down unused domains regardless.
> >
> > Fix this by adding checks to the sync_state helpers and callbacks.
> > Factor out the printing of the warning message, to make sure it is
> > printed only once.
> >
> > Fixes: 002ebddd695a5399 ("pmdomain: core: Restore behaviour for disabling unused PM domains")
> > Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
> > ---
> > RFC as I have no need for this in upstream.
>
> I am trying to understand the use case and whether we should consider
> to land this upstream.
>
> Would you mind elaborating on how this is useful for you?
It is (currently) not useful for me, but it may be useful for others.
During work on a new SoC, someone had hardcoded "pd_ignore_unused"
in the kernel command line. After adding support for PM Domains on
that SoC, I noticed PM Domains were still powered down.
The issue is that pd_ignore_unused no longer does what it claims to do:
pd_ignore_unused
[PM]
Keep all power-domains already enabled by bootloader on,
even if no driver has claimed them. This is useful
for debug and development, but should not be
needed on a platform with proper driver support.
So IMO that should either be fixed, or the option should be removed.
Do you agree?
Thanks!
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
On Wed, 4 Mar 2026 at 12:06, Geert Uytterhoeven <geert@linux-m68k.org> wrote:
>
> Hi Ulf,
>
> On Wed, 4 Mar 2026 at 11:56, Ulf Hansson <ulf.hansson@linaro.org> wrote:
> > On Mon, 16 Feb 2026 at 19:47, Geert Uytterhoeven
> > <geert+renesas@glider.be> wrote:
> > > Since the introduction of the sync_state mechanism, the
> > > "pd_ignore_unused" kernel command line option doesn't really work
> > > anymore. While genpd_power_off_unused() still checks for that flag
> > > before powering down unused domains, the new sync_state callbacks lack
> > > such checks, thus powering down unused domains regardless.
> > >
> > > Fix this by adding checks to the sync_state helpers and callbacks.
> > > Factor out the printing of the warning message, to make sure it is
> > > printed only once.
> > >
> > > Fixes: 002ebddd695a5399 ("pmdomain: core: Restore behaviour for disabling unused PM domains")
> > > Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
> > > ---
> > > RFC as I have no need for this in upstream.
> >
> > I am trying to understand the use case and whether we should consider
> > to land this upstream.
> >
> > Would you mind elaborating on how this is useful for you?
>
> It is (currently) not useful for me, but it may be useful for others.
> During work on a new SoC, someone had hardcoded "pd_ignore_unused"
> in the kernel command line. After adding support for PM Domains on
> that SoC, I noticed PM Domains were still powered down.
>
> The issue is that pd_ignore_unused no longer does what it claims to do:
>
> pd_ignore_unused
> [PM]
> Keep all power-domains already enabled by bootloader on,
> even if no driver has claimed them. This is useful
> for debug and development, but should not be
> needed on a platform with proper driver support.
>
Well, this is exactly what the sync_state mechanism intends to
address, but in a more correct way compared to pd_ignore_unused.
If a consumer device that belongs to a power domain, lacks a driver
(or it never probes) then that power domain will not be powered-off by
genpd (if it was on a boot). For the pd_ignore_unused case, we may end
up powering off the genpd anyway, becuase child-domains being
powered-off, for example.
For incomplete drivers, the assumption is that the device attaches to
its genpd but runtime PM remains disabled for the device. In these
cases, genpd will not power-off the corresponding power domain.
> So IMO that should either be fixed, or the option should be removed.
> Do you agree?
Right, I think it's time to consider removing it, unless people still
find it useful ofcourse.
Do you want to send a patch that we can test/review or you prefer me
to handle it?
Kind regards
Uffe
Hi Ulf,
On Wed, 4 Mar 2026 at 12:52, Ulf Hansson <ulf.hansson@linaro.org> wrote:
> On Wed, 4 Mar 2026 at 12:06, Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> > On Wed, 4 Mar 2026 at 11:56, Ulf Hansson <ulf.hansson@linaro.org> wrote:
> > > On Mon, 16 Feb 2026 at 19:47, Geert Uytterhoeven
> > > <geert+renesas@glider.be> wrote:
> > > > Since the introduction of the sync_state mechanism, the
> > > > "pd_ignore_unused" kernel command line option doesn't really work
> > > > anymore. While genpd_power_off_unused() still checks for that flag
> > > > before powering down unused domains, the new sync_state callbacks lack
> > > > such checks, thus powering down unused domains regardless.
> > > >
> > > > Fix this by adding checks to the sync_state helpers and callbacks.
> > > > Factor out the printing of the warning message, to make sure it is
> > > > printed only once.
> > > >
> > > > Fixes: 002ebddd695a5399 ("pmdomain: core: Restore behaviour for disabling unused PM domains")
> > > > Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
> > > > ---
> > > > RFC as I have no need for this in upstream.
> > >
> > > I am trying to understand the use case and whether we should consider
> > > to land this upstream.
> > >
> > > Would you mind elaborating on how this is useful for you?
> >
> > It is (currently) not useful for me, but it may be useful for others.
> > During work on a new SoC, someone had hardcoded "pd_ignore_unused"
> > in the kernel command line. After adding support for PM Domains on
> > that SoC, I noticed PM Domains were still powered down.
> >
> > The issue is that pd_ignore_unused no longer does what it claims to do:
> >
> > pd_ignore_unused
> > [PM]
> > Keep all power-domains already enabled by bootloader on,
> > even if no driver has claimed them. This is useful
> > for debug and development, but should not be
> > needed on a platform with proper driver support.
> >
[...]
> > So IMO that should either be fixed, or the option should be removed.
> > Do you agree?
>
> Right, I think it's time to consider removing it, unless people still
> find it useful ofcourse.
>
> Do you want to send a patch that we can test/review or you prefer me
> to handle it?
Feel free to handle it.
Thanks!
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
© 2016 - 2026 Red Hat, Inc.