[Public]
> -----Original Message-----
> From: Rafael J. Wysocki <rjw@xxxxxxxxxxxxx>
> Sent: Wednesday, July 13, 2022 13:51
> To: Linux ACPI <linux-acpi@xxxxxxxxxxxxxxx>
> Cc: LKML <linux-kernel@xxxxxxxxxxxxxxx>; Linux PM <linux-
> pm@xxxxxxxxxxxxxxx>; Srinivas Pandruvada
> <srinivas.pandruvada@xxxxxxxxxxxxxxx>; Zhang Rui <rui.zhang@xxxxxxxxx>;
> Limonciello, Mario <Mario.Limonciello@xxxxxxx>
> Subject: [PATCH] ACPI: PM: s2idle: Use LPS0 idle if
> ACPI_FADT_LOW_POWER_S0 is unset
>
> From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
>
> If the PNP0D80 device is present and its _DSM appears to be valid,
> there is no reason to avoid using it even if ACPI_FADT_LOW_POWER_S0
> is unset in the FADT, because suspend-to-idle may be the only way to
> suspend the system if S3 is not supported by the platform, so do not
> return early from lps0_device_attach() in that case.
>
> However, still check ACPI_FADT_LOW_POWER_S0 when deciding whether or
> not suspend-to-idle should be the default system suspend method.
>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> ---
Reviewed-by: Mario Limonciello <mario.limonciello@xxxxxxx>
> drivers/acpi/x86/s2idle.c | 11 +++++------
> 1 file changed, 5 insertions(+), 6 deletions(-)
>
> Index: linux-pm/drivers/acpi/x86/s2idle.c
> ==========================================================
> =========
> --- linux-pm.orig/drivers/acpi/x86/s2idle.c
> +++ linux-pm/drivers/acpi/x86/s2idle.c
> @@ -369,9 +369,6 @@ static int lps0_device_attach(struct acp
> if (lps0_device_handle)
> return 0;
>
> - if (!(acpi_gbl_FADT.flags & ACPI_FADT_LOW_POWER_S0))
> - return 0;
> -
> if (acpi_s2idle_vendor_amd()) {
> /* AMD0004, AMD0005, AMDI0005:
> * - Should use rev_id 0x0
> @@ -421,10 +418,12 @@ static int lps0_device_attach(struct acp
> lpi_device_get_constraints();
>
> /*
> - * Use suspend-to-idle by default if the default suspend mode was
> not
> - * set from the command line.
> + * Use suspend-to-idle by default if ACPI_FADT_LOW_POWER_S0 is
> set in
> + * the FADT and the default suspend mode was not set from the
> command
> + * line.
> */
> - if (mem_sleep_default > PM_SUSPEND_MEM &&
> !acpi_sleep_default_s3)
> + if ((acpi_gbl_FADT.flags & ACPI_FADT_LOW_POWER_S0) &&
> + mem_sleep_default > PM_SUSPEND_MEM &&
> !acpi_sleep_default_s3)
> mem_sleep_current = PM_SUSPEND_TO_IDLE;
>
> /*
>
>
