From: Rafael J. Wysocki rafael.j.wysocki@intel.com
commit c02d5feb6e2f60affc6ba8606d8d614c071e2ba6 upstream.
When _PPC returns 0, it means that the CPU frequency is not limited by the platform firmware, so make acpi_processor_get_platform_limit() update the frequency QoS request used by it to "no limit" in that case.
This addresses a problem with limiting CPU frequency artificially on some systems after CPU offline/online to the frequency that corresponds to the first entry in the _PSS return package.
Reported-by: Pratyush Yadav ptyadav@amazon.de Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Reviewed-by: Pratyush Yadav ptyadav@amazon.de Tested-by: Pratyush Yadav ptyadav@amazon.de Tested-by: Hagar Hemdan hagarhem@amazon.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/acpi/processor_perflib.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-)
--- a/drivers/acpi/processor_perflib.c +++ b/drivers/acpi/processor_perflib.c @@ -56,6 +56,8 @@ static int acpi_processor_get_platform_l { acpi_status status = 0; unsigned long long ppc = 0; + s32 qos_value; + int index; int ret;
if (!pr) @@ -75,17 +77,27 @@ static int acpi_processor_get_platform_l return -ENODEV; }
+ index = ppc; + pr_debug("CPU %d: _PPC is %d - frequency %s limited\n", pr->id, - (int)ppc, ppc ? "" : "not"); + index, index ? "is" : "is not");
- pr->performance_platform_limit = (int)ppc; + pr->performance_platform_limit = index;
if (ppc >= pr->performance->state_count || unlikely(!freq_qos_request_active(&pr->perflib_req))) return 0;
- ret = freq_qos_update_request(&pr->perflib_req, - pr->performance->states[ppc].core_frequency * 1000); + /* + * If _PPC returns 0, it means that all of the available states can be + * used ("no limit"). + */ + if (index == 0) + qos_value = FREQ_QOS_MAX_DEFAULT_VALUE; + else + qos_value = pr->performance->states[index].core_frequency * 1000; + + ret = freq_qos_update_request(&pr->perflib_req, qos_value); if (ret < 0) { pr_warn("Failed to update perflib freq constraint: CPU%d (%d)\n", pr->id, ret);