Re: [RFC v1 7/8] PM: hibernate: Enter s2idle sleep state before hibernation

[Antheas Kapenekakis]

On Fri, 13 Mar 2026 at 21:33, Rafael J. Wysocki <rafael@xxxxxxxxxx> wrote:
>
> On Fri, Dec 26, 2025 at 11:27 AM Antheas Kapenekakis <lkml@xxxxxxxxxxx> wrote:
> >
> > Implement the standby states as part of hibernation. Specifically,
> > ensure we are in the inactive state before hibernation entry, and
> > sync the state as active after hibernation resume. In case of a failed
> > hibernation, restore the previous standby state.
>
> We've not mixed up "modern standby" _DSM calls with hibernation so
> far, so this change is potentially risky.

Hi,
this patch can be dropped. I added it because I found in certain
devices, entering the hibernation flow and the subsequent ad hoc
reattaching of the USB subsystem to store the hibernation image can
cause these devices to turn on their vibration motor and leave it
stuck until hibernation completes (here, I assume the underlying cause
is the device briefly vibrates when initializing, but due to absent
initialization, it ends up stuck in that state).

So it is a bug fix. In any case, the commit message should state as
much if it is kept.

Antheas

> > Signed-off-by: Antheas Kapenekakis <lkml@xxxxxxxxxxx>
> > ---
> >  kernel/power/hibernate.c | 29 +++++++++++++++++++++++++++--
> >  1 file changed, 27 insertions(+), 2 deletions(-)
> >
> > diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
> > index af8d07bafe02..85a5ca8f6537 100644
> > --- a/kernel/power/hibernate.c
> > +++ b/kernel/power/hibernate.c
> > @@ -787,7 +787,11 @@ static int load_image_and_restore(void)
> >   */
> >  int hibernate(void)
> >  {
> > +#ifdef CONFIG_SUSPEND
> > +       standby_state_t previous_standby;
> > +#endif
> >         bool snapshot_test = false;
> > +       bool powered_down = false;
> >         unsigned int sleep_flags;
> >         int error;
> >
> > @@ -815,6 +819,13 @@ int hibernate(void)
> >         }
> >
> >         pr_info("hibernation entry\n");
> > +
> > +#if CONFIG_SUSPEND
> > +       /* Enter the standby screen off state in case userspace has not. */
> > +       previous_standby = pm_standby_get_state();
> > +       pm_standby_transition(PM_STANDBY_INACTIVE);
> > +#endif
> > +
> >         pm_prepare_console();
> >         error = pm_notifier_call_chain_robust(PM_HIBERNATION_PREPARE, PM_POST_HIBERNATION);
> >         if (error)
> > @@ -867,10 +878,12 @@ int hibernate(void)
> >                 error = swsusp_write(flags);
> >                 swsusp_free();
> >                 if (!error) {
> > -                       if (hibernation_mode == HIBERNATION_TEST_RESUME)
> > +                       if (hibernation_mode == HIBERNATION_TEST_RESUME) {
> >                                 snapshot_test = true;
> > -                       else
> > +                       } else {
> > +                               powered_down = true;
> >                                 power_down();
> > +                       }
> >                 }
> >                 in_suspend = 0;
> >                 pm_restore_gfp_mask();
> > @@ -897,6 +910,18 @@ int hibernate(void)
> >   Notify:
> >         pm_notifier_call_chain(PM_POST_HIBERNATION);
> >   Restore:
> > +#if CONFIG_SUSPEND
> > +       /*
> > +        * If we resumed from S5, we are in the active standby state. However,
> > +        * the kernel restored a stale value. Sync it. Otherwise, in e.g., the
> > +        * case of a failed hibernation, transition to the previous value.
> > +        */
> > +       if (powered_down)
> > +               pm_standby_set_state(PM_STANDBY_ACTIVE);
> > +       else
> > +               pm_standby_transition(previous_standby);
> > +#endif
> > +
> >         pm_restore_console();
> >         hibernate_release();
> >   Unlock:
> > --
> > 2.52.0
> >
> >
> >
>