Commit ec6c0503 authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
Browse files

ACPI: PM: x86: Print messages regarding LPS0 idle support 



Because suspend-to-idle is always supported and on x86 it is the only
way to suspend the system if S3 is not supported by the platform, the
kernel attempts to enter low-power S0 idle in the suspend-to-idle flow
regardless of whether or not the ACPI_FADT_LOW_POWER_S0 flag is set in
the FADT.  However, if that flag is not set, residency counters
associated with low-power S0 idle may not count and the platform may
refuse to put the EC into a low-power mode, for example.

For this reason, print diagnostic messages when the platform should
achieve significant energy savings in low-power S0 idle (because the
ACPI_FADT_LOW_POWER_S0 flag is set in the FADT) and when
suspend-to-idle becomes the default suspend method (because low-power
S0 idle should be equally or more efficient than S3, if available).

Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: default avatarMario Limonciello <mario.limonciello@amd.com>
parent 1a2dcab5

drivers/acpi/sleep.c

+3 −0
Original line number Diff line number Diff line
@@ -824,6 +824,9 @@ static const struct platform_s2idle_ops acpi_s2idle_ops = { 


void __weak acpi_s2idle_setup(void)

{

	if (acpi_gbl_FADT.flags & ACPI_FADT_LOW_POWER_S0)

		pr_info("Efficient low-power S0 idle declared\n");



	s2idle_set_ops(&acpi_s2idle_ops);

}

drivers/acpi/x86/s2idle.c

+3 −1
Original line number Diff line number Diff line
@@ -423,8 +423,10 @@ static int lps0_device_attach(struct acpi_device *adev, 
	 * line.

	 */

	if ((acpi_gbl_FADT.flags & ACPI_FADT_LOW_POWER_S0) &&

	    mem_sleep_default > PM_SUSPEND_MEM && !acpi_sleep_default_s3)

	    mem_sleep_default > PM_SUSPEND_MEM && !acpi_sleep_default_s3) {

		mem_sleep_current = PM_SUSPEND_TO_IDLE;

		pr_info("Low-power S0 idle used by default for system suspend\n");

	}



	/*

	 * Some LPS0 systems, like ASUS Zenbook UX430UNR/i7-8550U, require the