linux-kernel - Re: [PATCH 1/6] regulator: core: Allow simultaneous use of enable op and GPIO

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Date:	Thu, 23 Jun 2016 10:10:35 +0900
From:	Alexandre Courbot <gnurou@...il.com>
To:	Mark Brown <broonie@...nel.org>
Cc:	Alexandre Courbot <acourbot@...dia.com>,
	Liam Girdwood <lgirdwood@...il.com>,
	Rob Herring <robh+dt@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Subject: Re: [PATCH 1/6] regulator: core: Allow simultaneous use of enable op
 and GPIO

On Wed, Jun 22, 2016 at 7:34 PM, Mark Brown <broonie@...nel.org> wrote:
> On Wed, Jun 22, 2016 at 05:25:53PM +0900, Alexandre Courbot wrote:
>> The current regulator enable/disable mechanism does not call the driver
>> enable/disable op if an enable GPIO is set. It may be desirable to use
>> both mechanisms though, e.g. in the case of a PWM regulator that also
>> has an enable GPIO.
>>
>> _regulator_is_enabled() is also updated in order to take both enable
>> conditions into account.
>
> This is going to break or at least reduce the performance of a lot of
> users - it is very common for regulators to have configurable support
> for a GPIO enable in addition to a register enable with the GPIO enable
> replacing a register enable for improved performance.

Ah, I wasn't aware of this.

> If you have some
> strange device that requires GPIO and other operations the driver should
> handle that, if nothing else it's likely that there are sequencing
> requirements between the two which we are probably not going to get
> right for everyone in the core.

Having dedicated enable GPIO code in the PWM driver sounded redundant
since we already have the same in the core, which is why I went for
this approach. But with your above point it seems like I have no
choice.

Will rework this and send a simpler change to just pwm-regulator, thanks!