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ACPI: processor: perflib: Use the "no limit" frequency QoS

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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>
This commit is contained in:
Rafael J. Wysocki 2022-12-28 22:21:49 +01:00
parent fbf757e55a
commit c02d5feb6e
1 changed files with 17 additions and 5 deletions
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22
drivers/acpi/processor_perflib.c
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@ -53,6 +53,8 @@ static int acpi_processor_get_platform_limit(struct acpi_processor *pr)
{
acpi_status status = 0;
unsigned long long ppc = 0;
s32 qos_value;
int index;
int ret;
if (!pr)
@ -72,17 +74,27 @@ static int acpi_processor_get_platform_limit(struct acpi_processor *pr)
}
}
pr_debug("CPU %d: _PPC is %d - frequency %s limited\n", pr->id,
(int)ppc, ppc ? "" : "not");
index = ppc;
pr->performance_platform_limit = (int)ppc;
pr_debug("CPU %d: _PPC is %d - frequency %s limited\n", pr->id,
index, index ? "is" : "is not");
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);