This is a note to let you know that I've just added the patch titled
ACPI: processor: perflib: Use the "no limit" frequency QoS
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
acpi-processor-perflib-use-the-no-limit-frequency-qos.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From c02d5feb6e2f60affc6ba8606d8d614c071e2ba6 Mon Sep 17 00:00:00 2001
From: "Rafael J. Wysocki" <rafael.j.wysocki@xxxxxxxxx>
Date: Wed, 28 Dec 2022 22:21:49 +0100
Subject: ACPI: processor: perflib: Use the "no limit" frequency QoS
From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
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@xxxxxxxxx>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Reviewed-by: Pratyush Yadav <ptyadav@xxxxxxxxx>
Tested-by: Pratyush Yadav <ptyadav@xxxxxxxxx>
Tested-by: Hagar Hemdan <hagarhem@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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
@@ -53,6 +53,8 @@ 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)
@@ -72,17 +74,27 @@ static int acpi_processor_get_platform_l
}
}
+ 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);
Patches currently in stable-queue which might be from rafael.j.wysocki@xxxxxxxxx are
queue-5.15/acpi-processor-perflib-use-the-no-limit-frequency-qos.patch
queue-5.15/cpufreq-intel_pstate-drop-acpi-_pss-states-table-patching.patch
queue-5.15/acpi-processor-perflib-avoid-updating-frequency-qos-unnecessarily.patch
queue-5.15/serial-qcom-geni-drop-bogus-runtime-pm-state-update.patch
