Re: [PATCH v4 1/2] PM / Domains: Add support for 'required-opps' to set default perf state

[Rajendra Nayak]

On 7/17/2021 1:49 AM, Stephen Boyd wrote:
> Quoting Rajendra Nayak (2021-07-16 03:00:57)
> > Some devics within power domains with performance states do not
>
> devices
>
> > support DVFS, but still need to vote on a default/static state
> > while they are active. They can express this using the 'required-opps'
> > property in device tree, which points to the phandle of the OPP
> > supported by the corresponding power-domains.
> >
> > Add support to parse this information from DT and then set the
> > specified performance state during attach and drop it on detach.
> > Also drop/set as part of runtime suspend/resume callbacks.
> >
> > Signed-off-by: Rajendra Nayak <rnayak@xxxxxxxxxxxxxx>
> > ---
> >   drivers/base/power/domain.c | 37 ++++++++++++++++++++++++++++++++++---
> >   include/linux/pm_domain.h   |  1 +
> >   2 files changed, 35 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> > index a934c67..dcc0b71 100644
> > --- a/drivers/base/power/domain.c
> > +++ b/drivers/base/power/domain.c
> > @@ -1000,6 +1008,8 @@ static int genpd_runtime_resume(struct device *dev)
> >          genpd_stop_dev(genpd, dev);
> >   err_poweroff:
> >          if (!pm_runtime_is_irq_safe(dev) || genpd_is_irq_safe(genpd)) {
> > +               if (default_pstate)
> > +                       dev_pm_genpd_set_performance_state(dev, 0);
> >                  genpd_lock(genpd);
> >                  gpd_data->rpm_pstate = genpd_drop_performance_state(dev);
>
> Maybe this should be
>
> 		  prev_state = genpd_drop_performance_state(dev);
> 		  if (!default_pstate)
> 		  	gdp_data->rpm_pstate = prev_state;
>
> so we don't call dev_pm_genpd_set_performance_state() effectively twice?
> Also it would make sure we call dev_pm_genpd_set_performance_state()
> underneath the genpd_lock() if that is important. Similarly do that on
> suspend path.

looking through this more, I think I can completely drop any special
handling for default_pstate in runtime suspend and resume. The existing
drop/restore login Ulf has added should take care of it.
I'll test and respin soon.

> >                  genpd_power_off(genpd, true, 0);
> > @@ -2598,6 +2608,12 @@ static void genpd_dev_pm_detach(struct device *dev, bool power_off)
> >
> >          dev_dbg(dev, "removing from PM domain %s\n", pd->name);
> >
> > +       /* Drop the default performance state */
> > +       if (dev_gpd_data(dev)->default_pstate) {
> > +               dev_pm_genpd_set_performance_state(dev, 0);
> > +               dev_gpd_data(dev)->default_pstate = 0;
> > +       }
> > +
> >          for (i = 1; i < GENPD_RETRY_MAX_MS; i <<= 1) {
> >                  ret = genpd_remove_device(pd, dev);
> >                  if (ret != -EAGAIN)
> > @@ -2675,10 +2692,24 @@ static int __genpd_dev_pm_attach(struct device *dev, struct device *base_dev,
> >                  genpd_unlock(pd);
> >          }
> >
> > -       if (ret)
> > +       if (ret) {
> >                  genpd_remove_device(pd, dev);
> > +               return -EPROBE_DEFER;
> > +       }
> > +
> > +       /* Set the default performance state */
> > +       np = base_dev->of_node;
> > +       if (of_parse_phandle(np, "required-opps", index)) {
> > +               pstate = of_get_required_opp_performance_state(np, index);
> > +               if (pstate < 0) {
> > +                       dev_err(dev, "failed to set pstate:%d", pstate);
>
> Missing newline on printk. Also can we spell out pstate as "failed to
> set required performance state %d for power-domain %d"?

thanks, will fix when I respin.
Thanks for the review.

> > +                       ret = pstate;
> > +               }
> > +               dev_pm_genpd_set_performance_state(dev, pstate);
> > +               dev_gpd_data(dev)->default_pstate = pstate;
> > +       }
> >
> > -       return ret ? -EPROBE_DEFER : 1;
> > +       return ret ? ret : 1;
> >   }
> >
> >   /**

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