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From: Axel Lin <axel.lin@gmail.com>
Date: Tue, 24 Apr 2012 10:09:00 +0800
Message-ID: <CAF+7xWkzy5e0rcpwprEE3VWTikOu2+qtsgfdhTN12-yonDxadA@mail.gmail.com>
Subject: Re: [PATCH] leds: lm3530: fix handling of already enabled regulators
To: Mark Brown <broonie@opensource.wolfsonmicro.com>
Cc: linux-kernel@vger.kernel.org,
        Shreshtha Kumar Sahu <shreshthakumar.sahu@stericsson.com>,
        "Milo(Woogyom) Kim" <milo.kim@ti.com>,
        Richard Purdie <rpurdie@rpsys.net>,
        Andrew Morton <akpm@linux-foundation.org>, Liam Girdwood <lrg@ti.com>
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2012/4/23 Mark Brown <broonie@opensource.wolfsonmicro.com>:
> On Sun, Apr 22, 2012 at 11:11:48PM +0800, Axel Lin wrote:
>
>>               drvdata->regulator = NULL;
>>               goto err_regulator_get;
>>       }
>> +     drvdata->enable = regulator_is_enabled(drvdata->regulator);
>>
>
> This isn't sufficient for what the driver is doing - it also needs to
> enable the regulator.  Regulator enables are reference counted (since
> the regulator can be shared by many device supplies) so if this driver
> doesn't reference the regulator when it's needed then it could get
> powered off.

The regulator_enable() is called in lm3530_init_registers().

>
> If this regulator is the actual LED then the current default of assuming
> the regulator is off on boot isn't ideal either as it means that if the
> regulator is enabled on boot then the LED may be left on even though the
> driver thinks it's off.

Hi Shreshtha,
I think without this patch you can see the symptom Mark mentioned if the
regulator is enabled on boot.
Any chance to test if this patch works or not?

Regards,
Axel