RE: [PATCH][RFC,v4] ACPI / PM: Introduce efi poweroff for HW-full platforms without _S5

From: Chen, Yu C
Date: Wed Mar 16 2016 - 01:59:55 EST

Hi Matt,

> -----Original Message-----
> From: Matt Fleming [mailto:matt@xxxxxxxxxxxxxxxxxxx]
> Sent: Tuesday, March 15, 2016 4:01 AM
> To: Chen, Yu C
> Cc: linux-acpi@xxxxxxxxxxxxxxx; linux-pm@xxxxxxxxxxxxxxx; Rafael J. Wysocki;
> Len Brown; Thomas Gleixner; Ingo Molnar; H. Peter Anvin; Zhang, Rui; linux-
> efi@xxxxxxxxxxxxxxx; x86@xxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Ard
> Biesheuvel; Mark Salter
> Subject: Re: [PATCH][RFC,v4] ACPI / PM: Introduce efi poweroff for HW-full
> platforms without _S5
> On Fri, 11 Mar, at 04:33:46PM, Chen, Yu C wrote:
> >
> > There is a future Base-IA platform, we are planning to skip
> > implementing the SLP_TYP register and the S5 object. (already there
> > will be no S3 and no S4)
> Cool. This is really valuable information that should go into the commit
> message.
> Because if this is the rationale for the change, I don't see why we'd need to
> provide the default stuff. Instead we should just enforce EFI reboot, and
> only add the pm_poweroff_default hook if there is an explicit user in the
> future, IMO.

Do you mean the patch v3 make sense
and we should use efi power off as our first choice, if there is no _S5 available(no acpi_power_off),
even there is a customized poweroff(driver provided, eg)?

Meanwhile, the legacy platforms will not be affected because
there is no path to overwrite pm_power_off to efi power off.