Re: [RFC PATCH] gpio: add GPIO hogging mechanism

Felipe Balbi
2013-12-19T18:23:21Z

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On Thu, Dec 19, 2013 at 06:18:40PM +0100, boris brezillon wrote:
> Hello Felipe,
>
> On 19/12/2013 17:47, Felipe Balbi wrote:
> >On Thu, Dec 19, 2013 at 08:41:09AM -0800, Greg Kroah-Hartman wrote:
> >>On Thu, Dec 19, 2013 at 03:34:31PM +0100, Boris BREZILLON wrote:
> >>>GPIO hogging is a way to request and configure specific GPIO without
> >>>explicitly requesting it in the device driver.
> >>>
> >>>The request and configuration procedure is handled in the core device
> >>>driver code before the driver probe function is called.
> >>>
> >>>It allows specific GPIOs to be configured without any driver specific code.
> >>>
> >>>Particularly usefull when a external device is connected to a bus and the
> >>>bus connections depends on an external switch controlled by a GPIO pin.
> >for external switches, you probably need a pinctrl-gpio driver.
> >
> Do you mean using pinctrl pinconf to configure the PIN as output-high or
> output-low ?
>
> This was my first proposal
> (see https://www.mail-archive.com/devicetree@vger.kernel.org/msg05829.html).

that's quite a weird argument from Linus W, considering you _do_ have a
discrete mux on the board.

We have quite a few of such "crazy" scenarios here at TI and we were
going to send a pinctrl-gpio driver. If that's not acceptable, then I
suppose there is no way to boot from NAND on a board where NAND signals
go through a discrete mux where the select signal is a GPIO pin.

--
balbi

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