Re: [PATCH -next] cpufreq: userspace: Keep the current frequency when set userspace policy

[Zeng Heng]

在 2023/10/25 19:18, Viresh Kumar 写道:
> On 25-10-23, 16:09, Zeng Heng wrote:
> > When switching to the userspace policy, if the current frequency is within
> > the range of policy's min and max values, the current frequency value
> > should be remained. The .limit() function is called when changing governor
> > or updating governor limits, so in both cases, there is no need to update
> > frequency if the current frequency does not exceed the threshold.
> >
> > Additionally, when changing to userspace governor, the default value of
> > set_speed is set by reading the current frequency of the CPU, but there
> > is inevitable error between the frequency coming from .get_rate() interface
> > and the actual working frequency. Consequently, when switching to userspace
> > policy, keeping the current frequency can avoid unexpected changes.
> >
> > Signed-off-by: Zeng Heng <zengheng4@xxxxxxxxxx>
> > ---
> >   drivers/cpufreq/cpufreq_userspace.c | 4 +---
> >   1 file changed, 1 insertion(+), 3 deletions(-)
> >
> > diff --git a/drivers/cpufreq/cpufreq_userspace.c b/drivers/cpufreq/cpufreq_userspace.c
> > index 2c42fee76daa..fe55a7bb663c 100644
> > --- a/drivers/cpufreq/cpufreq_userspace.c
> > +++ b/drivers/cpufreq/cpufreq_userspace.c
> > @@ -117,9 +117,7 @@ static void cpufreq_userspace_policy_limits(struct cpufreq_policy *policy)
> >   	else if (policy->min > userspace->setspeed)
> >   		__cpufreq_driver_target(policy, policy->min,
> >   					CPUFREQ_RELATION_L);
> > -	else
> > -		__cpufreq_driver_target(policy, userspace->setspeed,
> > -					CPUFREQ_RELATION_L);
> > +	/* Otherwise, keep the current frequency. */
> >
> >   	mutex_unlock(&userspace->mutex);
> >   }
> Here is some reasoning why it should be done the way it is:
>
> commit e43e94c1eda7 ("cpufreq: Fix GOV_LIMITS handling for the userspace governor")


Get it, thanks for the response.

Zeng Heng