linux-kernel - Re: [PATCH v3] PM / OPP: discard duplicate OPPs

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Message-ID: <CAKohpokwBK5gMU30CrN8KymyoMsDY-XtWU1vH6x927qqn9YCkQ@mail.gmail.com>
Date:	Tue, 20 May 2014 19:06:29 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	Nishanth Menon <nm@...com>
Cc:	Chander Kashyap <chander.kashyap@...aro.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Pavel Machek <pavel@....cz>,
	"Brown, Len" <len.brown@...el.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Chander Kashyap <k.chander@...sung.com>,
	Inderpal Singh <inderpal.s@...sung.com>
Subject: Re: [PATCH v3] PM / OPP: discard duplicate OPPs

On 20 May 2014 18:02, Nishanth Menon <nm@...com> wrote:
>> +               if (new_opp->u_volt == opp->u_volt)
>> +                       ret = -EEXIST;

As I mentioned in the other mail in same thread, I screwed up
again. I meant a s/==/!= here..

In words:
- If we are adding duplicate OPPs (both freq/volt same), return 0 as
we already have that.
- if we are adding OPPs with same key (same freq, diff volt), return
-EEXIST and also print both old and new values of both freq and volt.

> Else -> we now have two OPPs with the same key (same frequency, but
> different voltage) -> That does not make sense.
> Example: why would you add:
> If you already had {1GHz, 1.2V}
> and you attempted:
> {1GHz, 1.1V} (if you could do that, then you should added {1GHz, 1.1V}
> in the first place)
> OR
> {1GHz, 1.3V} (if you could do that, then you should add {1GHz, 1.3V}
> and the {1GHz, 1.2V} is wrong)

Exactly, this is why I wanted to return -EEXIST here with some prints.
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