Re: [PATCH v2 19/48] opp: Fix adding OPP entries in a wrong order if rate is unavailable

[Viresh Kumar]

On 23-12-20, 23:36, Dmitry Osipenko wrote:
> 23.12.2020 07:34, Viresh Kumar пишет:
> > On 22-12-20, 22:19, Dmitry Osipenko wrote:
> >> 22.12.2020 12:12, Viresh Kumar пишет:
> >>> rate will be 0 for both the OPPs here if rate_not_available is true and so this
> >>> change shouldn't be required.
> >>
> >> The rate_not_available is negated in the condition. This change is
> >> required because both rates are 0 and then we should proceed to the
> >> levels comparison.
> > 
> > Won't that happen without this patch ?
> 
> No

This is how the code looks like currently:

int _opp_compare_key(struct dev_pm_opp *opp1, struct dev_pm_opp *opp2)
{
	if (opp1->rate != opp2->rate)
		return opp1->rate < opp2->rate ? -1 : 1;
	if (opp1->bandwidth && opp2->bandwidth &&
	    opp1->bandwidth[0].peak != opp2->bandwidth[0].peak)
		return opp1->bandwidth[0].peak < opp2->bandwidth[0].peak ? -1 : 1;
	if (opp1->level != opp2->level)
		return opp1->level < opp2->level ? -1 : 1;
	return 0;
}

Lets consider the case you are focussing on, where rate is 0 for both the OPPs,
bandwidth isn't there and we want to run the level comparison here.

Since both the rates are 0, (opp1->rate != opp2->rate) will fail and so we will
move to bandwidth check which will fail too. And so we will get to the level
comparison.

What am I missing here ? I am sure there is something for sure as you won't have
missed this..

-- 
viresh