Re: [PATCH] cpufreq: respect the min/max settings from user space

[Vince Hsu]

Hi Viresh,

Could you remind me where can I find this patch upstream? It seems this 
was missed?

Thanks,
Vince

On 10/06/2014 12:50 PM, Vince Hsu wrote:
> Hi Viresh,
>
> On 10/06/2014 12:45 PM, Viresh Kumar wrote:
> > On 2 October 2014 12:25, Vince Hsu <vinceh@xxxxxxxxxx> wrote:
> > > When the user space tries to set scaling_(max|min)_freq through
> > > sysfs, the cpufreq_set_policy() asks other driver's opinions
> > > for the max/min frequencies. Some device drivers, like Tegra
> > > CPU EDP which is not upstreamed yet though, may constrain the
> > > CPU maximum frequency dynamically because of board design.
> > > So if the user space access happens and some driver is capping
> > > the cpu frequency at the same time, the user_policy->(max|min)
> > > is overridden by the capped value, and that's not expected by
> > > the user space. And if the user space is not invoked again,
> > > the CPU will always be capped by the user_policy->(max|min)
> > > even no drivers limit the CPU frequency any more.
> > >
> > > This patch preserves the user specified min/max settings, so that
> > > every time the cpufreq policy is updated, the new max/min can
> > > be re-evaluated correctly based on the user's expection and
> > > the present device drivers' status.
> > >
> > > Signed-off-by: Vince Hsu <vinceh@xxxxxxxxxx>
> > > ---
> > > Hi,
> > >
> > > I'm not sure if any platform that is supported mainlin might have this
> > > issue, and this patch is complie tested only.
> > Why only compiled tested? Why haven't you tested it on tegra?
> I did test with Chrome kernel on Tegra platform. I can't do that with 
> mainline kernel because we haven't had the CPU EDP driver upstream yet.
>
> Thanks,
> Vince
>
> > >   drivers/cpufreq/cpufreq.c | 6 ++++--
> > >   1 file changed, 4 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> > > index 24bf76fba141..c007cf2a3d2a 100644
> > > --- a/drivers/cpufreq/cpufreq.c
> > > +++ b/drivers/cpufreq/cpufreq.c
> > > @@ -524,7 +524,7 @@ static int cpufreq_set_policy(struct 
> > > cpufreq_policy *policy,
> > >   static ssize_t 
> > > store_##file_name                                       \
> > >   (struct cpufreq_policy *policy, const char *buf, size_t 
> > > count)         \
> > > { \
> > > -       int 
> > > ret;                                                        \
> > > +       int ret, temp;                                          \
> > >          struct cpufreq_policy 
> > > new_policy;                               \
> > > \
> > >          ret = cpufreq_get_policy(&new_policy, 
> > > policy->cpu);             \
> > > @@ -535,8 +535,10 @@ static ssize_t 
> > > store_##file_name                                   \
> > >          if (ret != 
> > > 1)                                                   \
> > >                  return 
> > > -EINVAL;                                         \
> > > \
> > > +       temp = 
> > > new_policy.object;                                       \
> > >          ret = cpufreq_set_policy(policy, &new_policy);          \
> > > -       policy->user_policy.object = 
> > > policy->object;                    \
> > > +       if 
> > > (!ret)                                                       \
> > > +               policy->user_policy.object = 
> > > temp;                      \
> > > \
> > >          return ret ? ret : 
> > > count;                                       \
> > >   }
> > Looks fine otherwise.
> >
> > Acked-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
>
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