RE: [PATCH] ACPI: Execute the _PTS method when system reboot

[Zheng, Lv]

Hi,

> From: linux-acpi-owner@xxxxxxxxxxxxxxx [mailto:linux-acpi-
> owner@xxxxxxxxxxxxxxx] On Behalf Of Ocean HY1 He
> Subject: RE: [PATCH] ACPI: Execute the _PTS method when system reboot
> 
> Hi Rafael,
> Please see my reply in below.
> 
> Regards,
> Ocean He
> SW Development Dept.
> Beijing Design Center
> Enterprise Product Group
> Mobile: 18911778926
> E-mail: hehy1@xxxxxxxxxx
> No.6 Chuang Ye Road, Haidian District, Beijing, China 100085
> 
> > -----Original Message-----
> > From: Rafael J. Wysocki [mailto:rjw@xxxxxxxxxxxxx]
> > Sent: Wednesday, June 22, 2016 7:56 AM
> > To: Ocean HY1 He
> > Cc: lenb@xxxxxxxxxx; linux-acpi@xxxxxxxxxxxxxxx;
> > linux-kernel@xxxxxxxxxxxxxxx; David Tanaka; Nagananda Chumbalkar
> > Subject: Re: [PATCH] ACPI: Execute the _PTS method when system
> reboot
> >
> > On Monday, May 09, 2016 05:50:11 AM Ocean HY1 He wrote:
> > > The _PTS control method is defined in the section 7.4.1 of acpi 6.0
> > > spec. The _PTS control method is executed by the OS during the sleep
> > > transition process for S1, S2, S3, S4, and for orderly S5 shutdown.
> > > The sleeping state value (For example, 1, 2, 3, 4 or 5 for the S5
> > > soft-off state) is passed to the _PTS control method. This method
> > > is called after OSPM has notified native device drivers of the sleep
> > > state transition and before the OSPM has had a chance to fully
> > > prepare the system for a sleep state transition.
> > >
> > > The _PTS control method provides the BIOS a mechanism for
> performing
> > > some housekeeping, such as writing the sleep type value to the
> > embedded
> > > controller, before entering the system sleeping state.
> > >
> > > According to section 7.5 of acpi 6.0 spec, _PTS should run after _TTS.
> > >
> > > Thus, a _PTS block notifier is added to the reboot notifier list so that
> > > the _PTS object will also be evaluated when the system reboot.
> >
> > So I understand why it may be necessary to evaluate _PTS before
> entering
> > S5,
> > but I'm totally unsure about reboot.
> >
> > What does reboot have to do with S5?
> >
> In ACPI spec, there is no explicit words saying _PTS should be
> executed when reboot. But reboot could be equal to the
> process S0->S5->S0. Thus _PTS should be executed when reboot.
> 
> I am thinking this is the same as _TTS. In ACPI spec, there is also
> no explicit words saying _TTS should be executed when reboot.
> But kernel executes _TTS when reboot indeed.
[Lv Zheng] 
What's the de-facto standard behavior here?
Lenovo should be able to modify BIOS, should you try to boot different Windows clones to confirm the necessity of doing this?

Thanks and best regards
-Lv

> 
> > > Signed-off-by: Ocean He <hehy1@xxxxxxxxxx>
> > > Signed-off-by: Nagananda Chumbalkar <nchumbalkar@xxxxxxxxxx>
> > > ---
> > >  drivers/acpi/sleep.c | 27 +++++++++++++++++++++++++++
> > >  1 file changed, 27 insertions(+)
> > >
> > > diff --git a/drivers/acpi/sleep.c b/drivers/acpi/sleep.c
> > > index 2a8b596..8b290fb 100644
> > > --- a/drivers/acpi/sleep.c
> > > +++ b/drivers/acpi/sleep.c
> > > @@ -55,6 +55,26 @@ static struct notifier_block tts_notifier = {
> > >  	.priority	= 0,
> > >  };
> > >
> > > +static int pts_notify_reboot(struct notifier_block *this,
> > > +			unsigned long code, void *x)
> > > +{
> > > +	acpi_status status;
> > > +
> > > +	status = acpi_execute_simple_method(NULL, "\\_PTS",
> > ACPI_STATE_S5);
> > > +	if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) {
> > > +		/* It won't break anything. */
> > > +		printk(KERN_NOTICE "Failure in evaluating _PTS object\n");
> > > +	}
> > > +
> > > +	return NOTIFY_DONE;
> > > +}
> > > +
> > > +static struct notifier_block pts_notifier = {
> > > +	.notifier_call	= pts_notify_reboot,
> > > +	.next		= NULL,
> > > +	.priority	= 0,
> > > +};
> > > +
> > >  static int acpi_sleep_prepare(u32 acpi_state)
> > >  {
> > >  #ifdef CONFIG_ACPI_SLEEP
> > > @@ -896,5 +916,12 @@ int __init acpi_sleep_init(void)
> > >  	 * object can also be evaluated when the system enters S5.
> > >  	 */
> > >  	register_reboot_notifier(&tts_notifier);
> > > +
> > > +	/*
> > > +	 * According to section 7.5 of acpi 6.0 spec, _PTS should run after
> > > +	 * _TTS when the system enters S5.
> > > +	 */
> > > +	register_reboot_notifier(&pts_notifier);
> >
> > Why do you have to add a second notifier?
> >
> > Why can't _TTS and _PTS be evaluated from one notifier?
> >
> If execute _PTS method in tts_notify_reboot(), then it would break
> definition of tts_notify_reboot(). My intention is to keep new codes
> has limited impact on existed codes.
> Of course, it's possible to merge _TTS and _PTS into one unified notifier.
> The advantage is more actions could be added into the unified notifier in
> future.
> Which way you prefer?
> > > +
> > >  	return 0;
> > >  }
> > >
> >
> > Thanks,
> > Rafael
> 
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