On Thu, Dec 19, 2013 at 06:18:40PM +0100, boris brezillon wrote:

Hello Felipe,

On 19/12/2013 17:47, Felipe Balbi wrote:

quoted

On Thu, Dec 19, 2013 at 08:41:09AM -0800, Greg Kroah-Hartman wrote:

quoted

On Thu, Dec 19, 2013 at 03:34:31PM +0100, Boris BREZILLON wrote:

quoted

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