ACPI: PM: s2idle: Use LPS0 idle if ACPI_FADT_LOW_POWER_S0 is unset

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@intel.com>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>

diff --git a/drivers/acpi/x86/s2idle.c b/drivers/acpi/x86/s2idle.c
index 392f751..c1e5c3d 100644 (file)
--- a/drivers/acpi/x86/s2idle.c
+++ b/drivers/acpi/x86/s2idle.c
@@ -369,9 +369,6 @@ static int lps0_device_attach(struct acpi_device *adev,
        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 acpi_device *adev,
                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;
 
        /*