From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Modify acpi_processor_get_platform_limit() to avoid updating its
frequency QoS request when the _PPC return value has not changed
by comparing that value to the previous _PPC return value stored in
the performance_platform_limit field of the struct acpi_processor
corresponding to the given CPU.
While at it, do the _PPC return value check against the state count
earlier to avoid setting performance_platform_limit to an invalid value.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
---
v1 -> v2:
* New patch.
* Contains some changes from the previous [1/2] and a change to reset
performance_platform_limit on QoS request creation.
---
drivers/acpi/processor_perflib.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)
Index: linux-pm/drivers/acpi/processor_perflib.c
===================================================================
--- linux-pm.orig/drivers/acpi/processor_perflib.c
+++ linux-pm/drivers/acpi/processor_perflib.c
@@ -76,13 +76,16 @@ static int acpi_processor_get_platform_l
index = ppc;
+ if (pr->performance_platform_limit == index ||
+ ppc >= pr->performance->state_count)
+ return 0;
+
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)))
+ if (unlikely(!freq_qos_request_active(&pr->perflib_req)))
return 0;
/*
@@ -178,6 +181,13 @@ void acpi_processor_ppc_init(struct cpuf
if (!pr)
continue;
+ /*
+ * Reset performance_platform_limit in case there is a stale
+ * value in it, so as to make it match the "no limit" QoS value
+ * below.
+ */
+ pr->performance_platform_limit = 0;
+
ret = freq_qos_add_request(&policy->constraints,
&pr->perflib_req,
FREQ_QOS_MAX, INT_MAX);
