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

Hi Matt,

-----Original Message-----
From: Matt Fleming [mailto:matt@codeblueprint.co.uk]
Sent: Tuesday, March 15, 2016 4:01 AM
To: Chen, Yu C
Cc: linux-acpi@vger.kernel.org; linux-pm@vger.kernel.org; Rafael J. Wysocki;
Len Brown; Thomas Gleixner; Ingo Molnar; H. Peter Anvin; Zhang, Rui; linux-
efi@vger.kernel.org; x86@kernel.org; linux-kernel@vger.kernel.org; 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:

quoted

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
https://patchwork.kernel.org/patch/8514751/
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.

thanks,
yu