On Mon, Sep 15, 2025 at 03:18:44PM +0200, Rafael J. Wysocki wrote:
The question is not about who's fault it is, but what's the best place to address this issue.
I think that addressing it in cpufreq_policy_transition_delay_us() is a bit confusing because it is related to initialization and the new branch becomes pure overhead for the drivers that don't set cpuinfo.transition_latency to CPUFREQ_ETERNAL.
However, addressing it at the initialization time would effectively mean that the core would do something like:
if (policy->cpuinfo.transition_latency == CPUFREQ_ETERNAL) policy->cpuinfo.transition_latency = CPUFREQ_DEFAULT_TANSITION_LATENCY_NS;
but then it would be kind of more straightforward to update everybody using CPUFREQ_ETERNAL to set cpuinfo.transition_latency to CPUFREQ_DEFAULT_TANSITION_LATENCY_NS directly (and then get rid of CPUFREQ_ETERNAL entirely).
So we fix the regression with an immediate change like below, and then plan to remove CPUFREQ_ETERNAL entirely with another development series. Do I get you right?
---8<---
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index d873ff9add49..e37722ce7aec 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -574,6 +574,10 @@ unsigned int cpufreq_policy_transition_delay_us(struct cpufreq_policy *policy) if (policy->transition_delay_us) return policy->transition_delay_us;
+ if (policy->cpuinfo.transition_latency == CPUFREQ_ETERNAL) + policy->cpuinfo.transition_latency = + CPUFREQ_DEFAULT_TANSITION_LATENCY_NS; + latency = policy->cpuinfo.transition_latency / NSEC_PER_USEC; if (latency) /* diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h index 7fe0981a7e46..7331bc06f161 100644 --- a/include/linux/cpufreq.h +++ b/include/linux/cpufreq.h @@ -36,6 +36,8 @@ /* Print length for names. Extra 1 space for accommodating '\n' in prints */ #define CPUFREQ_NAME_PLEN (CPUFREQ_NAME_LEN + 1)
+#define CPUFREQ_DEFAULT_TANSITION_LATENCY_NS NSEC_PER_MSEC + struct cpufreq_governor;
enum cpufreq_table_sorting {
--->8---
Shawn