linux-kernel - Re: [RFC] dt: bindings: add bindings for Broadcom bcm43xx sdio devices

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Message-ID: <20140213162249.GT28112@sirena.org.uk>
Date:	Thu, 13 Feb 2014 16:22:49 +0000
From:	Mark Brown <broonie@...nel.org>
To:	Tomasz Figa <t.figa@...sung.com>
Cc:	Arend van Spriel <arend@...adcom.com>,
	Tomasz Figa <tomasz.figa@...il.com>,
	Rob Herring <robh+dt@...nel.org>, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, Chen-Yu Tsai <wens@...e.org>
Subject: Re: [RFC] dt: bindings: add bindings for Broadcom bcm43xx sdio
 devices

On Thu, Feb 13, 2014 at 01:35:41PM +0100, Tomasz Figa wrote:
> On 13.02.2014 13:07, Arend van Spriel wrote:
> >On 02/13/2014 10:13 AM, Tomasz Figa wrote:

> >>The BCM43xx WLAN chips I used to work always have been controlled by a
> >>simple power enable GPIO of the chip itself. Has this changed in newer
> >>chips?

> >>If you need to simply toggle a GPIO to control the power, you don't need
> >>to use the regulator API at all, controlling the GPIO directly.

> >Not sure I understand. Do you really mean 'chip' or 'wifi module' here.
> >The chip needs to be powered and for that it is hooked up to a
> >host/module provided GPIO (at least that is my understanding).

> Your binding asks for a regulator, not a simple GPIO, which is all I
> believe you need for BCM43xx power handling.

> Mark (added to Cc), could we get your opinion on this?

If it's a GPIO connected directly to the device it should be using
gpiolib, the fact that it happens to have an effect on power rather than
(say) just being a reset isn't terribly relevant to anything outside the
driver.  If it's an external regulator that happens to be controlled
using a GPIO on the current system then a regulator is better since
another system might use a regulator with a different control interface.

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