linux-kernel - Re: [RFC PATCH] gpio: add GPIO hogging mechanism

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20131219182227.GB4536@saruman.home>
Date:	Thu, 19 Dec 2013 12:22:27 -0600
From:	Felipe Balbi <balbi@...com>
To:	boris brezillon <b.brezillon@...rkiz.com>
CC:	<balbi@...com>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Rob Landley <rob@...dley.net>,
	Linus Walleij <linus.walleij@...aro.org>,
	Alexandre Courbot <gnurou@...il.com>,
	Jiri Prchal <jiri.prchal@...ignal.cz>,
	Ben Gamari <bgamari.foss@...il.com>,
	Mark Rutland <mark.rutland@....com>,
	<linux-doc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-gpio@...r.kernel.org>, <devicetree@...r.kernel.org>,
	Pekon Gupta <pekon@...com>,
	Linux OMAP Mailing List <linux-omap@...r.kernel.org>
Subject: Re: [RFC PATCH] gpio: add GPIO hogging mechanism

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

Download attachment "signature.asc" of type "application/pgp-signature" (837 bytes)