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| author | Qais Yousef <qyousef@layalina.io> | 2024-02-27 23:34:52 +0000 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2024-02-29 20:25:07 +0100 |
| commit | a755d0e2d41b9b0c7b4e0bc387c6225e3edba128 (patch) | |
| tree | 44a9a92a7fa4878ae1c8dc7d3557c290c7f6edf7 /drivers/cpufreq | |
| parent | d394abcb12bb1a6f309c1221fdb8e73594ecf1b4 (diff) | |
| download | linux-a755d0e2d41b9b0c7b4e0bc387c6225e3edba128.tar.gz | |
cpufreq: Honour transition_latency over transition_delay_us
Some platforms like Arm's Juno can have a high transition latency that
can be larger than the 2ms cap introduced. If a driver reports
a transition_latency that is higher than the cap, then use it as-is.
Update comment s/10/2/ to reflect the new cap of 2ms.
Reported-by: Pierre Gondois <pierre.gondois@arm.com>
Signed-off-by: Qais Yousef <qyousef@layalina.io>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/cpufreq')
| -rw-r--r-- | drivers/cpufreq/cpufreq.c | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 66cef33c4ec7b4..926a51cb7e52cd 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -576,8 +576,17 @@ unsigned int cpufreq_policy_transition_delay_us(struct cpufreq_policy *policy) latency = policy->cpuinfo.transition_latency / NSEC_PER_USEC; if (latency) { + unsigned int max_delay_us = 2 * MSEC_PER_SEC; + + /* + * If the platform already has high transition_latency, use it + * as-is. + */ + if (latency > max_delay_us) + return latency; + /* - * For platforms that can change the frequency very fast (< 10 + * For platforms that can change the frequency very fast (< 2 * us), the above formula gives a decent transition delay. But * for platforms where transition_latency is in milliseconds, it * ends up giving unrealistic values. @@ -586,7 +595,7 @@ unsigned int cpufreq_policy_transition_delay_us(struct cpufreq_policy *policy) * a reasonable amount of time after which we should reevaluate * the frequency. */ - return min(latency * LATENCY_MULTIPLIER, (unsigned int)(2 * MSEC_PER_SEC)); + return min(latency * LATENCY_MULTIPLIER, max_delay_us); } return LATENCY_MULTIPLIER; |