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

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Date:	Tue, 20 May 2014 08:36:15 -0500
From:	Nishanth Menon <nm@...com>
To:	Viresh Kumar <viresh.kumar@...aro.org>
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 05/20/2014 08:31 AM, Viresh Kumar wrote:
> On 20 May 2014 17:35, Viresh Kumar <viresh.kumar@...aro.org> wrote:
>> Though after more thought into this I feel this must also be done:
>>
>> diff --git a/drivers/base/power/opp.c b/drivers/base/power/opp.c
>> index bdf09f5..3f540d8 100644
>> --- a/drivers/base/power/opp.c
>> +++ b/drivers/base/power/opp.c
>> @@ -453,9 +453,13 @@ int dev_pm_opp_add(struct device *dev, unsigned
>> long freq, unsigned long u_volt)
>>         }
>>
>>         if (new_opp->rate == opp->rate) {
>> +               int ret = 0;
>> +
>> +               if (new_opp->u_volt == opp->u_volt)
>> +                       ret = -EEXIST;
>>                 mutex_unlock(&dev_opp_list_lock);
>>                 kfree(new_opp);
>> -               return 0;
>> +               return ret;
> 
> Ahh, sorry gentlemen. I have screwed up yet again.
> 
> I meant this instead:
> 
>> +               if (new_opp->u_volt != opp->u_volt)
>> +                       ret = -EEXIST;
> 
> Otherwise we are trying to add same OPP again and we can
> return zero.
> 
if it was added and disabled? I suggest:
new_opp->u_volt != opp->u_volt || !opp->available

I still dont like the idea that we are allowing folks to do:
{
	{1GHz 1.1V}
	{1GHz 1.1V}
	{1.2GHz 1.2V}
}

if you already had an OPP added and are trying to add it again, you
might want some debug ability. but anyways, with the mentioned check
above, my opposition is lower.

-- 
Regards,
Nishanth Menon
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