On Mon, Sep 22, 2025 at 08:31:56PM +0200, Rafael J. Wysocki wrote:
What about the appended (untested) change instead?
I'm trying to address a regression with a fix to be ported for stable kernel. Not really sure it's a good idea to mix up with cleanup changes.
Shawn
With a follow-up one to replace CPUFREQ_ETERNAL with something internal to CPPC.
Documentation/admin-guide/pm/cpufreq.rst | 4 ---- Documentation/cpu-freq/cpu-drivers.rst | 3 +-- Documentation/translations/zh_CN/cpu-freq/cpu-drivers.rst | 3 +-- Documentation/translations/zh_TW/cpu-freq/cpu-drivers.rst | 3 +-- drivers/cpufreq/cppc_cpufreq.c | 14 ++++++++++++-- drivers/cpufreq/cpufreq-dt.c | 2 +- drivers/cpufreq/imx6q-cpufreq.c | 2 +- drivers/cpufreq/mediatek-cpufreq-hw.c | 2 +- drivers/cpufreq/scmi-cpufreq.c | 2 +- drivers/cpufreq/scpi-cpufreq.c | 2 +- drivers/cpufreq/spear-cpufreq.c | 2 +- include/linux/cpufreq.h | 7 ++++--- 12 files changed, 25 insertions(+), 21 deletions(-)
--- a/Documentation/admin-guide/pm/cpufreq.rst +++ b/Documentation/admin-guide/pm/cpufreq.rst @@ -274,10 +274,6 @@ are the following: The time it takes to switch the CPUs belonging to this policy from one P-state to another, in nanoseconds.
- If unknown or if known to be so high that the scaling driver does not
- work with the `ondemand`_ governor, -1 (:c:macro:`CPUFREQ_ETERNAL`)
- will be returned by reads from this attribute.
``related_cpus`` List of all (online and offline) CPUs belonging to this policy. --- a/Documentation/cpu-freq/cpu-drivers.rst +++ b/Documentation/cpu-freq/cpu-drivers.rst @@ -109,8 +109,7 @@ Then, the driver must fill in the follow +-----------------------------------+--------------------------------------+ |policy->cpuinfo.transition_latency | the time it takes on this CPU to | | | switch between two frequencies in | -| | nanoseconds (if appropriate, else | -| | specify CPUFREQ_ETERNAL) | +| | nanoseconds | +-----------------------------------+--------------------------------------+ |policy->cur | The current operating frequency of | | | this CPU (if appropriate) | --- a/Documentation/translations/zh_CN/cpu-freq/cpu-drivers.rst +++ b/Documentation/translations/zh_CN/cpu-freq/cpu-drivers.rst @@ -112,8 +112,7 @@ CPUfreq核心层注册一个cpufreq_driv | | | +-----------------------------------+--------------------------------------+ |policy->cpuinfo.transition_latency | CPU在两个频率之间切换所需的时间，以 | -| | 纳秒为单位（如不适用，设定为 | -| | CPUFREQ_ETERNAL） | +| | 纳秒为单位 | | | | +-----------------------------------+--------------------------------------+ |policy->cur | 该CPU当前的工作频率(如适用) | --- a/Documentation/translations/zh_TW/cpu-freq/cpu-drivers.rst +++ b/Documentation/translations/zh_TW/cpu-freq/cpu-drivers.rst @@ -112,8 +112,7 @@ CPUfreq核心層註冊一個cpufreq_driv | | | +-----------------------------------+--------------------------------------+ |policy->cpuinfo.transition_latency | CPU在兩個頻率之間切換所需的時間，以 | -| | 納秒爲單位（如不適用，設定爲 | -| | CPUFREQ_ETERNAL） | +| | 納秒爲單位 | | | | +-----------------------------------+--------------------------------------+ |policy->cur | 該CPU當前的工作頻率(如適用) | --- a/drivers/cpufreq/cppc_cpufreq.c +++ b/drivers/cpufreq/cppc_cpufreq.c @@ -308,6 +308,16 @@ static int cppc_verify_policy(struct cpu return 0; } +static unsigned int get_transition_latency(unsigned int cpu) +{
- unsigned int transition_latency_ns = cppc_get_transition_latency(cpu);
- if (transition_latency_ns == CPUFREQ_ETERNAL)
return CPUFREQ_DEFAULT_TRANSITION_LATENCY_NS / NSEC_PER_USEC;- return transition_latency_ns / NSEC_PER_USEC;
+}
/*
- The PCC subspace describes the rate at which platform can accept commands
- on the shared PCC channel (including READs which do not count towards freq
@@ -330,12 +340,12 @@ static unsigned int cppc_cpufreq_get_tra return 10000; } }
- return cppc_get_transition_latency(cpu) / NSEC_PER_USEC;
- return get_transition_latency(cpu);
} #else static unsigned int cppc_cpufreq_get_transition_delay_us(unsigned int cpu) {
- return cppc_get_transition_latency(cpu) / NSEC_PER_USEC;
- return get_transition_latency(cpu);
} #endif --- a/drivers/cpufreq/cpufreq-dt.c +++ b/drivers/cpufreq/cpufreq-dt.c @@ -104,7 +104,7 @@ static int cpufreq_init(struct cpufreq_p transition_latency = dev_pm_opp_get_max_transition_latency(cpu_dev); if (!transition_latency)
transition_latency = CPUFREQ_ETERNAL;
transition_latency = CPUFREQ_DEFAULT_TRANSITION_LATENCY_NS;cpumask_copy(policy->cpus, priv->cpus); policy->driver_data = priv; --- a/drivers/cpufreq/imx6q-cpufreq.c +++ b/drivers/cpufreq/imx6q-cpufreq.c @@ -442,7 +442,7 @@ soc_opp_out: } if (of_property_read_u32(np, "clock-latency", &transition_latency))
transition_latency = CPUFREQ_ETERNAL;
transition_latency = CPUFREQ_DEFAULT_TRANSITION_LATENCY_NS;/* * Calculate the ramp time for max voltage change in the --- a/drivers/cpufreq/mediatek-cpufreq-hw.c +++ b/drivers/cpufreq/mediatek-cpufreq-hw.c @@ -309,7 +309,7 @@ static int mtk_cpufreq_hw_cpu_init(struc latency = readl_relaxed(data->reg_bases[REG_FREQ_LATENCY]) * 1000; if (!latency)
latency = CPUFREQ_ETERNAL;
latency = CPUFREQ_DEFAULT_TRANSITION_LATENCY_NS;policy->cpuinfo.transition_latency = latency; policy->fast_switch_possible = true; --- a/drivers/cpufreq/scmi-cpufreq.c +++ b/drivers/cpufreq/scmi-cpufreq.c @@ -294,7 +294,7 @@ static int scmi_cpufreq_init(struct cpuf latency = perf_ops->transition_latency_get(ph, domain); if (!latency)
latency = CPUFREQ_ETERNAL;
latency = CPUFREQ_DEFAULT_TRANSITION_LATENCY_NS;policy->cpuinfo.transition_latency = latency; --- a/drivers/cpufreq/scpi-cpufreq.c +++ b/drivers/cpufreq/scpi-cpufreq.c @@ -157,7 +157,7 @@ static int scpi_cpufreq_init(struct cpuf latency = scpi_ops->get_transition_latency(cpu_dev); if (!latency)
latency = CPUFREQ_ETERNAL;
latency = CPUFREQ_DEFAULT_TRANSITION_LATENCY_NS;policy->cpuinfo.transition_latency = latency; --- a/drivers/cpufreq/spear-cpufreq.c +++ b/drivers/cpufreq/spear-cpufreq.c @@ -182,7 +182,7 @@ static int spear_cpufreq_probe(struct pl if (of_property_read_u32(np, "clock-latency", &spear_cpufreq.transition_latency))
spear_cpufreq.transition_latency = CPUFREQ_ETERNAL;
spear_cpufreq.transition_latency = CPUFREQ_DEFAULT_TRANSITION_LATENCY_NS;cnt = of_property_count_u32_elems(np, "cpufreq_tbl"); if (cnt <= 0) { --- a/include/linux/cpufreq.h +++ b/include/linux/cpufreq.h @@ -26,12 +26,13 @@ *********************************************************************/ /*
- Frequency values here are CPU kHz
- Maximum transition latency is in nanoseconds - if it's unknown,
*/
- CPUFREQ_ETERNAL shall be used.
+/* Represents unknown transition latency */ #define CPUFREQ_ETERNAL (-1)
+#define CPUFREQ_DEFAULT_TANSITION_LATENCY_NS NSEC_PER_MSEC
#define CPUFREQ_NAME_LEN 16 /* Print length for names. Extra 1 space for accommodating '\n' in prints */ #define CPUFREQ_NAME_PLEN (CPUFREQ_NAME_LEN + 1)