linux-kernel - Re: [PATCH v4 2/2] PM: ACPI: reboot: Reinstate S5 for reboot

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Date:   Sat, 24 Sep 2022 18:19:01 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Kai-Heng Feng <kai.heng.feng@...onical.com>
Cc:     Rafael Wysocki <rafael.j.wysocki@...el.com>,
        Len Brown <lenb@...nel.org>,
        Josef Bacik <josef@...icpanda.com>,
        Dmitry Osipenko <dmitry.osipenko@...labora.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 2/2] PM: ACPI: reboot: Reinstate S5 for reboot

On Fri, Sep 16, 2022 at 6:33 AM Kai-Heng Feng
<kai.heng.feng@...onical.com> wrote:
>
> Commit d60cd06331a3 ("PM: ACPI: reboot: Use S5 for reboot") caused Dell
> PowerEdge r440 hangs at reboot.
>
> The issue is fixed by commit 2ca1c94ce0b6 ("tg3: Disable tg3 device on
> system reboot to avoid triggering AER"), so use the new sysoff API to
> reinstate S5 for reboot on ACPI-based systems.
>
> Using S5 for reboot is default behavior under Windows, "A full shutdown
> (S5) occurs when a system restart is requested" [1].
>
> [1] https://docs.microsoft.com/en-us/windows/win32/power/system-power-state
>
> Cc: Josef Bacik <josef@...icpanda.com>
> Suggested-by: Dmitry Osipenko <dmitry.osipenko@...labora.com>
> Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
> ---
> v4:
>  - Add comment and add more info to commit message.
> v3:
>  - Use new API to invoke ACPI S5.
> v2:
>  - Use do_kernel_power_off_prepare() instead.
>
>  drivers/acpi/sleep.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
>
> diff --git a/drivers/acpi/sleep.c b/drivers/acpi/sleep.c
> index ad4b2987b3d6e..0b557c0d405ef 100644
> --- a/drivers/acpi/sleep.c
> +++ b/drivers/acpi/sleep.c
> @@ -1088,6 +1088,14 @@ int __init acpi_sleep_init(void)
>                 register_sys_off_handler(SYS_OFF_MODE_POWER_OFF,
>                                          SYS_OFF_PRIO_FIRMWARE,
>                                          acpi_power_off, NULL);
> +
> +               /*
> +                * Windows uses S5 for reboot, so some BIOSes depend on it to
> +                * perform proper reboot.
> +                */
> +               register_sys_off_handler(SYS_OFF_MODE_RESTART_PREPARE,
> +                                        SYS_OFF_PRIO_FIRMWARE,
> +                                        acpi_power_off_prepare, NULL);
>         } else {
>                 acpi_no_s5 = true;
>         }
> --

Applied as 6.1 material with some edits in the changelog, thanks!