On Thursday, July 21, 2016 01:30:41 PM Viresh Kumar wrote:
> On 21-07-16, 22:31, Rafael J. Wysocki wrote:
> > On Thursday, July 21, 2016 12:59:26 PM Viresh Kumar wrote:
> > > On 13-07-16, 13:25, Steve Muckle wrote:
> > > > Cpufreq governors may need to know what a particular target frequency
> > > > maps to in the driver without necessarily wanting to set the frequency.
> > > > Support this operation via a new cpufreq API,
> > > > cpufreq_driver_resolve_freq(). This API returns the lowest driver
> > > > frequency equal or greater than the target frequency
> > > > (CPUFREQ_RELATION_L), subject to any policy (min/max) or driver
> > > > limitations. The mapping is also cached in the policy so that a
> > > > subsequent fast_switch operation can avoid repeating the same lookup.
> > > >
> > > > The API will call a new cpufreq driver callback, resolve_freq(), if it
> > > > has been registered by the driver. Otherwise the frequency is resolved
> > > > via cpufreq_frequency_table_target(). Rather than require ->target()
> > > > style drivers to provide a resolve_freq() callback it is left to the
> > > > caller to ensure that the driver implements this callback if necessary
> > > > to use cpufreq_driver_resolve_freq().
> > > >
> > > > Suggested-by: Rafael J. Wysocki <rafael.j.wyso...@intel.com>
> > > > Signed-off-by: Steve Muckle <smuc...@linaro.org>
> > > > ---
> > > > drivers/cpufreq/cpufreq.c | 25 +++++++++++++++++++++++++
> > > > include/linux/cpufreq.h | 16 ++++++++++++++++
> > > > 2 files changed, 41 insertions(+)
> > > >
> > > > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> > > > index 118b4f30a406..b696baeb249d 100644
> > > > --- a/drivers/cpufreq/cpufreq.c
> > > > +++ b/drivers/cpufreq/cpufreq.c
> > > > @@ -492,6 +492,29 @@ void cpufreq_disable_fast_switch(struct
> > > > cpufreq_policy *policy)
> > > > }
> > > > EXPORT_SYMBOL_GPL(cpufreq_disable_fast_switch);
> > > >
> > > > +/**
> > > > + * cpufreq_driver_resolve_freq - Map a target frequency to a
> > > > driver-supported
> > > > + * one.
> > > > + * @target_freq: target frequency to resolve.
> > > > + *
> > > > + * The target to driver frequency mapping is cached in the policy.
> > > > + *
> > > > + * Return: Lowest driver-supported frequency greater than or equal to
> > > > the
> > > > + * given target_freq, subject to policy (min/max) and driver
> > > > limitations.
> > > > + */
> > > > +unsigned int cpufreq_driver_resolve_freq(struct cpufreq_policy *policy,
> > > > + unsigned int target_freq)
> > > > +{
> > > > + target_freq = clamp_val(target_freq, policy->min, policy->max);
> > > > + policy->cached_target_freq = target_freq;
> > > > + if (cpufreq_driver->resolve_freq)
> > > > + return cpufreq_driver->resolve_freq(policy,
> > > > target_freq);
> > >
> > > Any reason why we still have this call around ? I thought the whole
> > > attempt I made was to get rid of this :)
> > >
> > > The core can do this pretty much now by itself, why do we still want
> > > this call?
> >
> > In case some drivers that don't use frequency tables want to implemet
> > fast switching, for example.
>
> Okay, but in that case shouldn't we do something like this:
That'd be fine by me.
Please send a patch on top of the Steve's series and I can apply it too
(unless Steve sees some major problems in it, which seems unlikely to me).
> unsigned int cpufreq_driver_resolve_freq(struct cpufreq_policy *policy,
> unsigned int target_freq)
> {
> target_freq = clamp_val(target_freq, policy->min, policy->max);
> policy->cached_target_freq = target_freq;
>
> if (cpufreq_driver->target_index) {
> policy->cached_resolved_idx =
> cpufreq_frequency_table_target(policy,
> target_freq,
>
> CPUFREQ_RELATION_L);
> return
> policy->freq_table[policy->cached_resolved_idx].frequency;
> }
>
> if (cpufreq_driver->resolve_freq)
> return cpufreq_driver->resolve_freq(policy, target_freq);
> }
>
> ??
Thanks,
Rafael
