Re: [Patch] cpufreq: tegra194: remove opp table in exit hook

[Sumit Gupta]

> > > > Add exit hook and remove OPP table when all the CPU's in a policy
> > > > are offlined. It will fix the below error messages when onlining
> > > > first CPU from a policy whose all CPU's were previously offlined.
> > > >
> > > >    debugfs: File 'cpu5' in directory 'opp' already present!
> > > >    debugfs: File 'cpu6' in directory 'opp' already present!
> > > >    debugfs: File 'cpu7' in directory 'opp' already present!
> > > >
> > > > Fixes: f41e1442ac5b ("cpufreq: tegra194: add OPP support and set bandwidth")
> > > > Signed-off-by: Sumit Gupta <sumitg@xxxxxxxxxx>
> > > > ---
> > > >    drivers/cpufreq/tegra194-cpufreq.c | 13 +++++++++++++
> > > >    1 file changed, 13 insertions(+)
> > > >
> > > > diff --git a/drivers/cpufreq/tegra194-cpufreq.c b/drivers/cpufreq/tegra194-cpufreq.c
> > > > index c90b30469165..66a9c23544db 100644
> > > > --- a/drivers/cpufreq/tegra194-cpufreq.c
> > > > +++ b/drivers/cpufreq/tegra194-cpufreq.c
> > > > @@ -454,6 +454,8 @@ static int tegra_cpufreq_init_cpufreq_table(struct cpufreq_policy *policy,
> > > >                 if (ret < 0)
> > > >                         return ret;
> > > >
> > > > +             dev_pm_opp_put(opp);
> > > > +
> > > >                 freq_table[j].driver_data = pos->driver_data;
> > > >                 freq_table[j].frequency = pos->frequency;
> > > >                 j++;
> > > > @@ -508,6 +510,16 @@ static int tegra194_cpufreq_init(struct cpufreq_policy *policy)
> > > >         return 0;
> > > >    }
> > > >
> > > > +static int tegra194_cpufreq_exit(struct cpufreq_policy *policy)
> > > > +{
> > > > +     struct device *cpu_dev = get_cpu_device(policy->cpu);
> > > > +
> > > > +     dev_pm_opp_remove_all_dynamic(cpu_dev);
> > > > +     dev_pm_opp_of_cpumask_remove_table(policy->related_cpus);
> > > > +
> > > > +     return 0;
> > > > +}
> > > > +
> > > >    static int tegra194_cpufreq_set_target(struct cpufreq_policy *policy,
> > > >                                        unsigned int index)
> > > >    {
> > > > @@ -535,6 +547,7 @@ static struct cpufreq_driver tegra194_cpufreq_driver = {
> > > >         .target_index = tegra194_cpufreq_set_target,
> > > >         .get = tegra194_get_speed,
> > > >         .init = tegra194_cpufreq_init,
> > > > +     .exit = tegra194_cpufreq_exit,
> > > >         .attr = cpufreq_generic_attr,
> > > >    };
> > >
> > > If it is only about hotplugging of the CPUs, then you can also do this I guess.
> > >
> > > commit 263abfe74b5f ("cpufreq: dt: Implement online/offline() callbacks")
>
> You should do this as well, this makes hotplugging paths much faster. i.e. on
> top of this patch.

Sent a separate patch to add online/offline callbacks.
  https://lore.kernel.org/lkml/20230825111920.8257-1-sumitg@xxxxxxxxxx/

Also, sent v2 of this patch with updated commit description.
  https://lore.kernel.org/lkml/20230825111617.8069-1-sumitg@xxxxxxxxxx/

Thank you,
Sumit Gupta

> > > But since your driver is capable of being built as a module, I suggest you try
> > > to build it as one and insert remove it multiple times. It must cause you some
> > > trouble as you don't implement an .exit() before this patch.
> > >
> > > Eventually, I think you need to do both, what this patch and 263abfe74b5f do.
> > > Just that the reasons need to be correct for both the changes.
> > >
> > > --
> > > viresh
> >
> > Hi Viresh,
> > I got the same message on inserting and removing the module multiple times
> > as you suggested. After applying this change, the message is not coming. So,
> > the current change is resolving both scenarios as __cpufreq_offline() calls
> > either exit() or offline().
> > I can update the commit message to mention both scenarios and keep change as
> > it is?
> >
> >    cpufreq_remove_dev
> >    |-__cpufreq_offline
> >    |--tegra194_cpufreq_exit
> >
> >    cpuhp_cpufreq_offline
> >    |-__cpufreq_offline
> >    |--tegra194_cpufreq_exit
>
> --
> viresh