linux-kernel - Re: [PATCH][v5] ACPI / PM: Introduce efi poweroff for HW-full platforms without

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Date:	Mon, 21 Mar 2016 13:43:18 +0100
From:	"Rafael J. Wysocki" <rafael@...nel.org>
To:	Chen Yu <yu.c.chen@...el.com>,
	Matt Fleming <matt@...eblueprint.co.uk>
Cc:	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	linux-efi@...r.kernel.org,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	x86@...nel.org, Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, Len Brown <lenb@...nel.org>
Subject: Re: [PATCH][v5] ACPI / PM: Introduce efi poweroff for HW-full
 platforms without _S5

On Sun, Mar 20, 2016 at 3:31 PM, Chen Yu <yu.c.chen@...el.com> wrote:
> 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. Since there will be HW-full mode where
> the DSDT fails to supply an _S5 object(without SLP_TYP), we
> should let such kind of platform to leverage efi runtime service
> to poweroff.
>
> This patch uses efi power off as first choice when S5 is
> unavailable, even if there is a customized poweroff(driver provided, eg).
> Meanwhile, the legacy platforms will not be affected because there is no
> path for them to overwrite the pm_power_off to efi power off.
>
> Suggested-by: Len Brown <len.brown@...el.com>
> Signed-off-by: Chen Yu <yu.c.chen@...el.com>
> ---
> v5:
>  - Revert to version 2, enforce EFI poweroff for such kind
>    of platforms.
> v4:
>  - Since in v3 efi_poweroff_required() is not guaranteed to run
>    after all of the other code that may register alternative
>    power off handling, add the pm_power_off_default that would
>    be used by pm_power_off if nothing else is available.
> 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           | 7 +++++++
>  include/linux/acpi.h           | 1 +
>  3 files changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c
> index ed30e79..7e5ec62 100644
> --- a/arch/x86/platform/efi/quirks.c
> +++ b/arch/x86/platform/efi/quirks.c
> @@ -340,5 +340,5 @@ bool efi_reboot_required(void)
>
>  bool efi_poweroff_required(void)
>  {
> -       return !!acpi_gbl_reduced_hardware;
> +       return acpi_gbl_reduced_hardware || acpi_no_s5;
>  }
> diff --git a/drivers/acpi/sleep.c b/drivers/acpi/sleep.c
> index 9cb9752..a33859c 100644
> --- a/drivers/acpi/sleep.c
> +++ b/drivers/acpi/sleep.c
> @@ -25,6 +25,11 @@
>  #include "internal.h"
>  #include "sleep.h"
>
> +/*
> + * Some HW-full platforms do not have _S5, so they may need
> + * to leverage efi power off for a shutdown.
> + */
> +bool acpi_no_s5;
>  static u8 sleep_states[ACPI_S_STATE_COUNT];
>
>  static void acpi_sleep_tts_switch(u32 acpi_state)
> @@ -846,6 +851,8 @@ int __init acpi_sleep_init(void)
>                 sleep_states[ACPI_STATE_S5] = 1;
>                 pm_power_off_prepare = acpi_power_off_prepare;
>                 pm_power_off = acpi_power_off;
> +       } else {
> +               acpi_no_s5 = true;
>         }
>
>         supported[0] = 0;
> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> index 06ed7e5..4d2e67f 100644
> --- a/include/linux/acpi.h
> +++ b/include/linux/acpi.h
> @@ -278,6 +278,7 @@ void acpi_irq_stats_init(void);
>  extern u32 acpi_irq_handled;
>  extern u32 acpi_irq_not_handled;
>  extern unsigned int acpi_sci_irq;
> +extern bool acpi_no_s5;
>  #define INVALID_ACPI_IRQ       ((unsigned)-1)
>  static inline bool acpi_sci_irq_valid(void)
>  {
> --

OK, this is fine by me.

Matt, what do you think?