Re: [PATCH v6 3/3] OPP: Add helper function for bandwidth OPP tables

[Saravana Kannan <saravanak@google.com>]

On Wed, Jan 8, 2020 at 3:19 AM Viresh Kumar <viresh.kumar@linaro.org> wrote:
>
> On 06-12-19, 16:24, Saravana Kannan wrote:
> > The frequency OPP tables have helper functions to search for entries in the
> > table based on frequency and get the frequency values for a given (or
> > suspend) OPP entry.
> >
> > Add similar helper functions for bandwidth OPP tables to search for entries
> > in the table based on peak bandwidth and to get the peak and average
> > bandwidth for a given (or suspend) OPP entry.
> >
> > Signed-off-by: Saravana Kannan <saravanak@google.com>
> > ---
> >  drivers/opp/core.c     | 301 +++++++++++++++++++++++++++++++++++------
> >  include/linux/pm_opp.h |  43 ++++++
> >  2 files changed, 305 insertions(+), 39 deletions(-)
> >
> > diff --git a/drivers/opp/core.c b/drivers/opp/core.c
> > index c79bbfac7289..3ff33a08198e 100644
> > --- a/drivers/opp/core.c
> > +++ b/drivers/opp/core.c
> > @@ -127,6 +127,29 @@ unsigned long dev_pm_opp_get_freq(struct dev_pm_opp *opp)
> >  }
> >  EXPORT_SYMBOL_GPL(dev_pm_opp_get_freq);
> >
> > +/**
> > + * dev_pm_opp_get_bw() - Gets the bandwidth corresponding to an available opp
> > + * @opp:     opp for which peak bandwidth has to be returned for
>
> s/peak //

Ack

>
> > + * @avg_bw:  Pointer where the corresponding average bandwidth is stored.
> > + *           Can be NULL.
> > + *
> > + * Return: Peak bandwidth in kBps corresponding to the opp, else
> > + * return 0
> > + */
> > +unsigned long dev_pm_opp_get_bw(struct dev_pm_opp *opp, unsigned long *avg_bw)
> > +{
> > +     if (IS_ERR_OR_NULL(opp) || !opp->available) {
> > +             pr_err("%s: Invalid parameters\n", __func__);
> > +             return 0;
> > +     }
> > +
> > +     if (avg_bw)
>
> Do you see this being NULL in practice ? If no, then we can make it
> mandatory for now ?

Yes, very likely. A lot of OPP tables might not have avg bandwidth listed.

> > +             *avg_bw = opp->avg_bw;
> > +
> > +     return opp->peak_bw;
> > +}
> > +EXPORT_SYMBOL_GPL(dev_pm_opp_get_bw);
> > +
> >  /**
> >   * dev_pm_opp_get_level() - Gets the level corresponding to an available opp
> >   * @opp:     opp for which level value has to be returned for
> > @@ -299,6 +322,34 @@ unsigned long dev_pm_opp_get_suspend_opp_freq(struct device *dev)
> >  }
> >  EXPORT_SYMBOL_GPL(dev_pm_opp_get_suspend_opp_freq);
> >
> > +/**
> > + * dev_pm_opp_get_suspend_opp_bw() - Get peak bandwidth of suspend opp in kBps
>
> Hmm, I wasn't expecting this. So the interconnects will also have a
> suspend OPP ?

Yes, device voting for interconnect paths might want to lower the
bandwidth to a suspend bandwidth when they suspend.

> > + * @dev:     device for which we do this operation
> > + * @avg_bw:  Pointer where the corresponding average bandwidth is stored.
> > + *           Can be NULL.
> > + *
> > + * Return: This function returns the peak bandwidth of the OPP marked as
> > + * suspend_opp if one is available, else returns 0;
> > + */
> > +unsigned long dev_pm_opp_get_suspend_opp_bw(struct device *dev,
> > +                                         unsigned long *avg_bw)
> > +{
> > +     struct opp_table *opp_table;
> > +     unsigned long peak_bw = 0;
> > +
> > +     opp_table = _find_opp_table(dev);
> > +     if (IS_ERR(opp_table))
> > +             return 0;
> > +
> > +     if (opp_table->suspend_opp && opp_table->suspend_opp->available)
> > +             peak_bw = dev_pm_opp_get_bw(opp_table->suspend_opp, avg_bw);
> > +
> > +     dev_pm_opp_put_opp_table(opp_table);
> > +
> > +     return peak_bw;
> > +}
> > +EXPORT_SYMBOL_GPL(dev_pm_opp_get_suspend_opp_bw);
> > +
> >  int _get_opp_count(struct opp_table *opp_table)
> >  {
> >       struct dev_pm_opp *opp;
> > @@ -343,6 +394,40 @@ int dev_pm_opp_get_opp_count(struct device *dev)
> >  }
> >  EXPORT_SYMBOL_GPL(dev_pm_opp_get_opp_count);
> >
>
> I think we should add function header here instead of the helpers
> which get exact match for freq, bw or level. And then pass a enum
> value to it, which tells what we are looking to compare. After that
> rest of the routines will be just one liners, make them macros in
> header file itself.

Not sure I understand what you are saying here.


> > +struct dev_pm_opp *dev_pm_opp_find_opp_exact(struct device *dev,
> > +                                           struct dev_pm_opp *opp_key,
> > +                                           bool available)
>

-Saravana