Re: [PATCH] cpufreq: use last policy after online

Rafael J. Wysocki
2015-12-02T01:35:46Z

On Tuesday, December 01, 2015 04:52:14 PM Srinivas Pandruvada wrote:
> For cpufreq drivers which use setpolicy interface, after offline->online
> the policy is set to default. This can be reproduced by setting the
> default policy of intel_pstate or longrun to ondemand and then change to
> "performance". After offline and online, the setpolicy will be called with
> the policy=ondemand.
> For drivers using governors this condition is handled by storing
> last_governor, during offline and restoring during online. The same should
> be done for drivers using setpolicy interface. Storing last_policy during
> offline and restoring during online.
>
> Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>

I guess this is urgent, right?

Is it a regression fix or has it just never worked?

> ---
> drivers/cpufreq/cpufreq.c | 14 ++++++++++----
> include/linux/cpufreq.h | 1 +
> 2 files changed, 11 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index a83c995..8412ce5 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -976,10 +976,14 @@ static int cpufreq_init_policy(struct cpufreq_policy *policy)
>
> new_policy.governor = gov;
>
> - /* Use the default policy if its valid. */
> - if (cpufreq_driver->setpolicy)
> - cpufreq_parse_governor(gov->name, &new_policy.policy, NULL);
> -
> + /* Use the default policy if there is no last_policy. */
> + if (cpufreq_driver->setpolicy) {
> + if (policy->last_policy)
> + new_policy.policy = policy->last_policy;
> + else
> + cpufreq_parse_governor(gov->name, &new_policy.policy,
> + NULL);
> + }
> /* set default policy */
> return cpufreq_set_policy(policy, &new_policy);
> }
> @@ -1330,6 +1334,8 @@ static void cpufreq_offline_prepare(unsigned int cpu)
> if (has_target())
> strncpy(policy->last_governor, policy->governor->name,
> CPUFREQ_NAME_LEN);
> + else
> + policy->last_policy = policy->policy;
> } else if (cpu == policy->cpu) {
> /* Nominate new CPU */
> policy->cpu = cpumask_any(policy->cpus);
> diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
> index ef4c5b1..177c768 100644
> --- a/include/linux/cpufreq.h
> +++ b/include/linux/cpufreq.h
> @@ -77,6 +77,7 @@ struct cpufreq_policy {
> unsigned int suspend_freq; /* freq to set during suspend */
>
> unsigned int policy; /* see above */
> + unsigned int last_policy; /* policy before unplug */
> struct cpufreq_governor *governor; /* see below */
> void *governor_data;
> bool governor_enabled; /* governor start/stop flag */
>

Thanks,
Rafael