linux-kernel - Re: [PATCH] PM: hibernate: Fix the bug where wake events cannot wake system during hibernation

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Date:   Mon, 6 Nov 2023 06:06:35 +0000
From:   Chris Feng (冯保林) 
        <Chris.Feng@...iatek.com>
To:     "rafael@...nel.org" <rafael@...nel.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        "stable@...nel.org" <stable@...nel.org>,
        "pavel@....cz" <pavel@....cz>,
        Hua Yang (杨华) <Hua.Yang@...iatek.com>,
        Liang Lu (吕亮) <liang.lu@...iatek.com>,
        Ting Wang (王挺) <ting.wang@...iatek.com>,
        "len.brown@...el.com" <len.brown@...el.com>
Subject: Re: [PATCH] PM: hibernate: Fix the bug where wake events cannot wake
 system during hibernation

Hi Rafael J,

On Fri, 2023-10-27 at 13:22 +0800, Chris Feng wrote:
> On Wed, 2023-10-25 at 20:28 +0200, Rafael J. Wysocki wrote:
> > On Tue, Oct 24, 2023 at 11:15 AM <chris.feng@...iatek.com> wrote:
> > > 
> > > ---
> > >  kernel/power/hibernate.c | 10 ++++++++--
> > >  1 file changed, 8 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
> > > index 8d35b9f9aaa3..16d8027a195d 100644
> > > --- a/kernel/power/hibernate.c
> > > +++ b/kernel/power/hibernate.c
> > > @@ -642,9 +642,9 @@ int hibernation_platform_enter(void)
> > >   */
> > >  static void power_down(void)
> > >  {
> > > -#ifdef CONFIG_SUSPEND
> > >         int error;
> > > 
> > > +#ifdef CONFIG_SUSPEND
> > >         if (hibernation_mode == HIBERNATION_SUSPEND) {
> > >                 error =
> > 
> > suspend_devices_and_enter(mem_sleep_current);
> > >                 if (error) {
> > > @@ -667,7 +667,13 @@ static void power_down(void)
> > >                 kernel_restart(NULL);
> > >                 break;
> > >         case HIBERNATION_PLATFORM:
> > > -               hibernation_platform_enter();
> > > +               error = hibernation_platform_enter();
> > > +               if (error) {
> > 
> > This error need not be -EAGAIN which means pending wakeup.  There
> > are
> > other errors that can be returned for which the fallback to
> > shutdown
> > is still desirable.
> > 
> 
> Thank you for your comments. I have some questions:
> In function hibernation_platform_enter(), if function
> dpm_suspend_start/end returns error, it goes to resume devices flow.
> After the system restores the devices, the system shuts down.  Is
> this
> expected design behivour?  If it is, would you help to give the
> design
> reasons in short ? From my point of view, since the deivces are
> resumed, why dose the system go to shut down state ? And also, after
> the system shuts down , and when the system is waked up by power key,
> the devices will be resumed again when restoring the saved system's
> image.
> 

We are looking forward to your reply.

> > > +                       swsusp_unmark();
> > > +                       events_check_enabled = false;
> > > +                       pr_err("Hibernation Abort.\n");
> > > +                       return;
> > > +               }
> > >                 fallthrough;
> > >         case HIBERNATION_SHUTDOWN:
> > >                 if (kernel_can_power_off())
> > > --
> > > 2.17.0
> > > 

Thanks!