From: Mario Limonciello mario.limonciello@amd.com
commit eb087f305919ee8169ad65665610313e74260463 upstream.
When `osc_pc_lpi_support_confirmed` is set through `_OSC` and `_LPI` is populated then the cpuidle driver assumes that LPI is fully functional.
However currently the kernel only provides architectural support for LPI on ARM. This leads to high power consumption on X86 platforms that otherwise try to enable LPI.
So probe whether or not LPI support is implemented before enabling LPI in the kernel. This is done by overloading `acpi_processor_ffh_lpi_probe` to check whether it returns `-EOPNOTSUPP`. It also means that all future implementations of `acpi_processor_ffh_lpi_probe` will need to follow these semantics as well.
Reviewed-by: Sudeep Holla sudeep.holla@arm.com Signed-off-by: Mario Limonciello mario.limonciello@amd.com Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/acpi/processor_idle.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-)
--- a/drivers/acpi/processor_idle.c +++ b/drivers/acpi/processor_idle.c @@ -1201,6 +1201,11 @@ static int flatten_lpi_states(struct acp return 0; }
+int __weak acpi_processor_ffh_lpi_probe(unsigned int cpu) +{ + return -EOPNOTSUPP; +} + static int acpi_processor_get_lpi_info(struct acpi_processor *pr) { int ret, i; @@ -1209,6 +1214,11 @@ static int acpi_processor_get_lpi_info(s struct acpi_device *d = NULL; struct acpi_lpi_states_array info[2], *tmp, *prev, *curr;
+ /* make sure our architecture has support */ + ret = acpi_processor_ffh_lpi_probe(pr->id); + if (ret == -EOPNOTSUPP) + return ret; + if (!osc_pc_lpi_support_confirmed) return -EOPNOTSUPP;
@@ -1260,11 +1270,6 @@ static int acpi_processor_get_lpi_info(s return 0; }
-int __weak acpi_processor_ffh_lpi_probe(unsigned int cpu) -{ - return -ENODEV; -} - int __weak acpi_processor_ffh_lpi_enter(struct acpi_lpi_state *lpi) { return -ENODEV;