Re: [PATCH v8 01/34] opp: Add dev_pm_opp_sync() helper

Viresh Kumar
2021-08-18T03:55:42Z

On 17-08-21, 18:49, Dmitry Osipenko wrote:
> 17.08.2021 10:55, Viresh Kumar пишет:
> ...
> >> +int dev_pm_opp_sync(struct device *dev)
> >> +{
> >> + struct opp_table *opp_table;
> >> + struct dev_pm_opp *opp;
> >> + int ret = 0;
> >> +
> >> + /* Device may not have OPP table */
> >> + opp_table = _find_opp_table(dev);
> >> + if (IS_ERR(opp_table))
> >> + return 0;
> >> +
> >> + if (!_get_opp_count(opp_table))
> >> + goto put_table;
> >> +
> >> + opp = _find_current_opp(dev, opp_table);
> >> + ret = _set_opp(dev, opp_table, opp, opp->rate);
> >
> > And I am not sure how this will end up working, since new OPP will be
> > equal to old one. Since I see you call this from resume() at many
> > places.
>
> Initially OPP table is "uninitialized" and opp_table->enabled=false,
> hence the first sync always works even if OPP is equal to old one. Once
> OPP has been synced, all further syncs are NO-OPs, hence it doesn't
> matter how many times syncing is called.
>
> https://elixir.bootlin.com/linux/v5.14-rc6/source/drivers/opp/core.c#L1012

Right, but how will this work from Resume ? Won't that be a no-op ?

--
viresh