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Power management fixes for 6.12-rc5

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Update cpufreq documentation to match the code after recent
 changes (Christian Loehle), fix a units conversion issue in the
 CPPC cpufreq driver (liwei), and fix an error check in the
 dtpm_devfreq power capping driver (Yuan Can).
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Merge tag 'pm-6.12-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

Pull power management fixes from Rafael Wysocki:
 "Update cpufreq documentation to match the code after recent changes
  (Christian Loehle), fix a units conversion issue in the CPPC cpufreq
  driver (liwei), and fix an error check in the dtpm_devfreq power
  capping driver (Yuan Can)"

* tag 'pm-6.12-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  cpufreq: CPPC: fix perf_to_khz/khz_to_perf conversion exception
  powercap: dtpm_devfreq: Fix error check against dev_pm_qos_add_request()
  cpufreq: docs: Reflect latency changes in docs
This commit is contained in:
Linus Torvalds 2024-10-25 11:00:50 -07:00
commit 8c76163fff
3 changed files with 28 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
Documentation/admin-guide/pm/cpufreq.rst
View File

@ -425,8 +425,8 @@ This governor exposes only one tunable:
``rate_limit_us``
Minimum time (in microseconds) that has to pass between two consecutive
runs of governor computations (default: 1000 times the scaling driver's
transition latency).
runs of governor computations (default: 1.5 times the scaling driver's
transition latency or the maximum 2ms).
The purpose of this tunable is to reduce the scheduler context overhead
of the governor which might be excessive without it.
@ -474,17 +474,17 @@ This governor exposes the following tunables:
This is how often the governor's worker routine should run, in
microseconds.
Typically, it is set to values of the order of 10000 (10 ms). Its
default value is equal to the value of ``cpuinfo_transition_latency``
for each policy this governor is attached to (but since the unit here
is greater by 1000, this means that the time represented by
``sampling_rate`` is 1000 times greater than the transition latency by
default).
Typically, it is set to values of the order of 2000 (2 ms). Its
default value is to add a 50% breathing room
to ``cpuinfo_transition_latency`` on each policy this governor is
attached to. The minimum is typically the length of two scheduler
ticks.
If this tunable is per-policy, the following shell command sets the time
represented by it to be 750 times as high as the transition latency::
represented by it to be 1.5 times as high as the transition latency
(the default)::
# echo `$(($(cat cpuinfo_transition_latency) * 750 / 1000)) > ondemand/sampling_rate
# echo `$(($(cat cpuinfo_transition_latency) * 3 / 2)) > ondemand/sampling_rate
``up_threshold``
If the estimated CPU load is above this value (in percent), the governor

22
drivers/acpi/cppc_acpi.c
View File

@ -1916,9 +1916,15 @@ unsigned int cppc_perf_to_khz(struct cppc_perf_caps *caps, unsigned int perf)
u64 mul, div;
if (caps->lowest_freq && caps->nominal_freq) {
mul = caps->nominal_freq - caps->lowest_freq;
/* Avoid special case when nominal_freq is equal to lowest_freq */
if (caps->lowest_freq == caps->nominal_freq) {
mul = caps->nominal_freq;
div = caps->nominal_perf;
} else {
mul = caps->nominal_freq - caps->lowest_freq;
div = caps->nominal_perf - caps->lowest_perf;
}
mul *= KHZ_PER_MHZ;
div = caps->nominal_perf - caps->lowest_perf;
offset = caps->nominal_freq * KHZ_PER_MHZ -
div64_u64(caps->nominal_perf * mul, div);
} else {
@ -1939,11 +1945,17 @@ unsigned int cppc_khz_to_perf(struct cppc_perf_caps *caps, unsigned int freq)
{
s64 retval, offset = 0;
static u64 max_khz;
u64 mul, div;
u64 mul, div;
if (caps->lowest_freq && caps->nominal_freq) {
mul = caps->nominal_perf - caps->lowest_perf;
div = caps->nominal_freq - caps->lowest_freq;
/* Avoid special case when nominal_freq is equal to lowest_freq */
if (caps->lowest_freq == caps->nominal_freq) {
mul = caps->nominal_perf;
div = caps->nominal_freq;
} else {
mul = caps->nominal_perf - caps->lowest_perf;
div = caps->nominal_freq - caps->lowest_freq;
}
/*
* We don't need to convert to kHz for computing offset and can
* directly use nominal_freq and lowest_freq as the div64_u64

2
drivers/powercap/dtpm_devfreq.c
View File

@ -178,7 +178,7 @@ static int __dtpm_devfreq_setup(struct devfreq *devfreq, struct dtpm *parent)
ret = dev_pm_qos_add_request(dev, &dtpm_devfreq->qos_req,
DEV_PM_QOS_MAX_FREQUENCY,
PM_QOS_MAX_FREQUENCY_DEFAULT_VALUE);
if (ret) {
if (ret < 0) {
pr_err("Failed to add QoS request: %d\n", ret);
goto out_dtpm_unregister;
}