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ACPI / PM: LPIT: Register sysfs attributes based on FADT

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ACPI Low Power S0 Idle capabilities are announced via FADT table and can
be used to inform the kernel about the presence of one or more Low Power
Idle (LPI) entries as descried in LPIT table. LPIT table can exist
independently even if the FADT S0 Idle flag is not set and thus it could
confuse user since the following cpuidle attributes are created.

/sys/devices/system/cpu/cpuidle/low_power_idle_cpu_residency_us
/sys/devices/system/cpu/cpuidle/low_power_idle_system_residency_us

Presence or absence of above attributes could mean that the given
platform supports S0ix state or not.

This change allows to create the above cpuidle attributes only if
FADT table supports Low Power S0 Idle.

Signed-off-by: Rajneesh Bhardwaj <rajneesh.bhardwaj@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Rajneesh Bhardwaj 2018-09-28 14:24:02 +05:30 committed by Rafael J. Wysocki
parent 17b57b1883
commit 1cdda9486f
1 changed files with 6 additions and 0 deletions
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6
drivers/acpi/acpi_lpit.c
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@ -117,11 +117,17 @@ static void lpit_update_residency(struct lpit_residency_info *info,
if (!info->iomem_addr)
return;
if (!(acpi_gbl_FADT.flags & ACPI_FADT_LOW_POWER_S0))
return;
/* Silently fail, if cpuidle attribute group is not present */
sysfs_add_file_to_group(&cpu_subsys.dev_root->kobj,
&dev_attr_low_power_idle_system_residency_us.attr,
"cpuidle");
} else if (info->gaddr.space_id == ACPI_ADR_SPACE_FIXED_HARDWARE) {
if (!(acpi_gbl_FADT.flags & ACPI_FADT_LOW_POWER_S0))
return;
/* Silently fail, if cpuidle attribute group is not present */
sysfs_add_file_to_group(&cpu_subsys.dev_root->kobj,
&dev_attr_low_power_idle_cpu_residency_us.attr,