Re: [PATCH 4/4] cpufreq: arm_big_little: add SCPI interface driver

[Sudeep Holla]

Hi Viresh,

Thanks for the review.

On 29/04/15 06:44, Viresh Kumar wrote:
> On 27 April 2015 at 17:10, Sudeep Holla <sudeep.holla@xxxxxxx> wrote:
> > diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
> > index 4f3dbc8cf729..9e678bf1687c 100644
> > --- a/drivers/cpufreq/Kconfig.arm
> > +++ b/drivers/cpufreq/Kconfig.arm
> > @@ -24,6 +24,15 @@ config ARM_VEXPRESS_SPC_CPUFREQ
> >             This add the CPUfreq driver support for Versatile Express
> >            big.LITTLE platforms using SPC for power management.
> >
> > +config ARM_SCPI_CPUFREQ
> > +        tristate "SCPI based CPUfreq driver"
> > +       depends on ARM_BIG_LITTLE_CPUFREQ && ARM_SCPI_PROTOCOL
> > +        help
> > +          This add the CPUfreq driver support for ARM big.LITTLE platforms
> > +         using SCPI interface for CPU power management.
> > +
> > +         This driver works only if firmware the supporting CPU DVFS adhere
> > +         to SCPI protocol.
>
> Wanna reword that ?

Ok


[...]

> > +static int scpi_init_opp_table(struct device *cpu_dev)
> > +{
> > +       u8 domain = topology_physical_package_id(cpu_dev->id);
> > +       struct scpi_dvfs_info *info;
> > +       struct scpi_opp *opp;
> > +       int idx, ret = 0;
> > +
> > +       if ((dev_pm_opp_get_opp_count(cpu_dev)) > 0)
> > +               return 0;
>
> Why, who would have added it ?

IIRC, it was added to prevent spurious duplicate OPP addition messages
during CPU hotplug. I will check it again.

> > +       info = scpi_ops->dvfs_get_info(domain);
>
> Isn't calling this twice costly for getting the same information ?

No the SCPI protocol saves them and return just the pointer if it's
already populated.

> > +       if (IS_ERR(info))
> > +               return PTR_ERR(info);
> > +
> > +       opp = info->opps;
> > +       if (!opp)
> > +               return -EIO;
> > +
> > +       for (idx = 0; idx < info->count; idx++, opp++) {
> > +               ret = dev_pm_opp_add(cpu_dev, opp->freq, opp->m_volt * 1000);
> > +               if (ret) {
> > +                       dev_warn(cpu_dev, "failed to add opp %uHz %umV\n",
> > +                                opp->freq, opp->m_volt);
>
> Don't you want to free earlier OPPs here ?

Make sense will fix.

> > +static struct cpufreq_arm_bL_ops scpi_cpufreq_ops = {
> > +       .name   = "scpi",
> > +       .get_transition_latency = scpi_get_transition_latency,
> > +       .init_opp_table = scpi_init_opp_table,
>
> Don't want to free/remove OPPs ?

Ah I see a new function is added, will fix it. In-fact this driver was
written before that and was held up since the firmware was not stable.

[...]

> > +static struct platform_driver scpi_cpufreq_platdrv = {
> > +       .driver = {
> > +               .name   = "scpi-cpufreq",
> > +               .owner  = THIS_MODULE,
> > +       },
> > +       .probe          = scpi_cpufreq_probe,
> > +       .remove         = scpi_cpufreq_remove,
> > +};
> > +module_platform_driver(scpi_cpufreq_platdrv);
> > +
> > +MODULE_LICENSE("GPL");
>
> GPL V2 ?
>
> Author/Description missing ..

Will fix it in next version.

Regards,
Sudeep
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