linux-kernel - Re: drivers/regulator/core.c: Fixes mapping inside regulator_mode_to_status() and makes it returning -EINVAL on invalid input.

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Date:	Tue, 10 Jan 2012 17:09:40 +0000
From:	dd diasemi <dd.diasemi@...il.com>
To:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: drivers/regulator/core.c: Fixes mapping inside
 regulator_mode_to_status() and makes it returning -EINVAL on invalid input.

On Tue, Jan 10, 2012 at 12:14 AM, Mark Brown
<broonie@...nsource.wolfsonmicro.com> wrote:
> On Tue, Jan 10, 2012 at 12:11:33AM +0000, dd diasemi wrote:
>
>> Making regulator_mode_to_status() returning an error allows to
>> simplify its usage:
>>       ret = regulator_mode_to_status(regulator_get_mode(rdev));
>>       if (ret < 0)
>>               ret = -EIO;
>
> That code would definitely be less than ideal - if we got an error back
> from the attempt to read the mode we ought to be returning that error
> not squashing it down to a single value.

Yes, indeed.

>> If that behaviour is deliberate, I would suggest to make it explicit:
>>       default:
>> -             return 0;
>> +             return REGULATOR_STATUS_OFF;
>
> That's not the deliberate behaviour, the deliberate behaviour is to
> return no mode if we didn't find one.

The behaviour is exactly the same in both cases, because
REGULATOR_STATUS_OFF == 0.

>From linux/regulator/driver.h:
enum regulator_status {
       REGULATOR_STATUS_OFF,
       REGULATOR_STATUS_ON,
       REGULATOR_STATUS_ERROR,
       /* fast/normal/idle/standby are flavors of "on" */
       REGULATOR_STATUS_FAST,
       REGULATOR_STATUS_NORMAL,
       REGULATOR_STATUS_IDLE,
       REGULATOR_STATUS_STANDBY,
};

So the only difference is that, the code:
       return 0;
is not obvious but still it will be interpreted as:
       return REGULATOR_STATUS_OFF;
by the caller of regulator_mode_to_status() when incorrect mode is passed.
Is it correct way to hide this behaviour rather than to make it explicit ?

And to set things up, should regulator_get_status() return negative
error code or REGULATOR_STATUS_OFF (0) on communication failure?
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