Hi Rafael,

-----Original Message-----
From: rjwysocki@gmail.com [mailto:rjwysocki@gmail.com] On Behalf Of
Rafael J. Wysocki
Sent: Monday, March 07, 2016 9:19 PM
To: Chen, Yu C
Cc: ACPI Devel Maling List; x86@kernel.org; linux-efi@vger.kernel.org; Linux
Kernel Mailing List; linux-pm@vger.kernel.org; Rafael J. Wysocki; Len Brown;
Matt Fleming; Thomas Gleixner; Ingo Molnar; H. Peter Anvin; Zhang, Rui
Subject: Re: [PATCH][RFC v3] ACPI / PM: Fix poweroff issue on HW-full
platforms without _S5

On Mon, Mar 7, 2016 at 3:50 AM, Chen Yu [off-list ref] wrote:

quoted

The problem is Linux registers pm_power_off = efi_power_off only if we
are in hardware reduced mode. Actually, what we also want is to do
this when ACPI S5 is simply not supported on non-legacy platforms.
That should handle both the HW reduced mode, and the HW-full mode
where the DSDT fails to supply an _S5 object.

This patch fixes this issue by introducing a new flag acpi_no_s5 which
indicates the non-existence of _S5. The initial state of acpi_no_s5 is
false and probed in acpi_sleep_init, then we'll later see the updated
value in efi_poweroff_required, according to which we can set
pm_power_off to efi_power_off in efi_shutdown_init, if no other

pm_power_off available.

quoted

Suggested-by: Len Brown <redacted>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
---
v3:
 - Only assign pm_power_off to efi_power_off when there are no
   other pm_power_off registered at that time, in case other
   commponents would like to customize their own implementation.
---
v2:
 - Convert the acpi_no_s5 to a global bool variable in sleep.c and
   add a declaration to include/linux/acpi.h.
---
 arch/x86/platform/efi/quirks.c | 2 +-
 drivers/acpi/sleep.c           | 8 ++++++++
 include/linux/acpi.h           | 1 +
 3 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/arch/x86/platform/efi/quirks.c

b/arch/x86/platform/efi/quirks.c index 2d66db8..0d4186b 100644

--- a/arch/x86/platform/efi/quirks.c
+++ b/arch/x86/platform/efi/quirks.c

@@ -295,5 +295,5 @@ bool efi_reboot_required(void)

 bool efi_poweroff_required(void)
 {
-       return !!acpi_gbl_reduced_hardware;
+       return acpi_gbl_reduced_hardware || (acpi_no_s5 &&
+ !pm_power_off);

What if CONFIG_ACPI is not set here?

If CONFIG_ACPI is not set, this file would not be compiled,
because CONFIG_EFI depends on CONFIG_ACPI.