linux-kernel - RE: [PATCH RFT] regulator: lp8788-ldo: Use ldo->en_pin to check if regulator is enabled by external pin

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Date:	Mon, 7 Jan 2013 23:23:26 +0000
From:	"Kim, Milo" <Milo.Kim@...com>
To:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
CC:	Axel Lin <axel.lin@...ics.com>, "Girdwood, Liam" <lrg@...com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH RFT] regulator: lp8788-ldo: Use ldo->en_pin to check if
 regulator is enabled by external pin

> -----Original Message-----
> From: Mark Brown [mailto:broonie@...nsource.wolfsonmicro.com]
> Sent: Monday, January 07, 2013 8:08 PM
> To: Axel Lin
> Cc: Kim, Milo; Girdwood, Liam; linux-kernel@...r.kernel.org
> Subject: Re: [PATCH RFT] regulator: lp8788-ldo: Use ldo->en_pin to
> check if regulator is enabled by external pin
> 
> On Sat, Jan 05, 2013 at 03:33:43PM +0800, Axel Lin wrote:
> > ldo->en_pin is set iff the regulator is enabled by external pin.
> >
> > This patch sets ldo->en_pin to NULL if lp8788_gpio_request_ldo_en()
> fails, then
> > we can use it to determinate if the regulator is controlled by
> external pin or
> > register.
> 
> Applied, thanks.  However we should be converting the driver to use the
> core support for this - the GPIO can just be given to the core in the
> regulator config which should handle everything transparently.

Thanks, Mark!

I have a question.
Do you mean the dependency of CONFIG_GENERIC_GPIO in this driver?

If yes, lp8788-ldo driver still works.
If the gpio_request_one() gets failed on loading the driver, then the lp8788-ldo
 driver refers to register based by default.
So LDOs can be enabled/disabled by the I2C, not external GPIO pins.
In that case, GPIO functions are not invoked any more.

Milo




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