4.18-stable review patch. If anyone has any objections, please let me know.
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From: Rajneesh Bhardwaj rajneesh.bhardwaj@linux.intel.com
[ Upstream commit 1cdda9486f5103fb133f88e662e48c504adbb779 ]
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 Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/acpi/acpi_lpit.c | 6 ++++++ 1 file changed, 6 insertions(+)
--- a/drivers/acpi/acpi_lpit.c +++ b/drivers/acpi/acpi_lpit.c @@ -117,11 +117,17 @@ static void lpit_update_residency(struct 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,