From mboxrd@z Thu Jan 1 00:00:00 1970 From: Felipe Balbi Subject: Re: [RFC PATCH] gpio: add GPIO hogging mechanism Date: Thu, 19 Dec 2013 12:22:27 -0600 Message-ID: <20131219182227.GB4536@saruman.home> References: <1387463671-1164-1-git-send-email-b.brezillon@overkiz.com> <1387463671-1164-2-git-send-email-b.brezillon@overkiz.com> <20131219164109.GB27409@kroah.com> <20131219164737.GA4536@saruman.home> <52B32A70.1080700@overkiz.com> Reply-To: Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="+g7M9IMkV8truYOl" Return-path: Content-Disposition: inline In-Reply-To: <52B32A70.1080700@overkiz.com> Sender: linux-kernel-owner@vger.kernel.org To: boris brezillon Cc: balbi@ti.com, Greg Kroah-Hartman , Rob Landley , Linus Walleij , Alexandre Courbot , Jiri Prchal , Ben Gamari , Mark Rutland , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-gpio@vger.kernel.org, devicetree@vger.kernel.org, Pekon Gupta , Linux OMAP Mailing List List-Id: linux-gpio@vger.kernel.org --+g7M9IMkV8truYOl Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Dec 19, 2013 at 06:18:40PM +0100, boris brezillon wrote: > Hello Felipe, >=20 > 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 ? >=20 > This was my first proposal > (see https://www.mail-archive.com/devicetree@vger.kernel.org/msg05829.htm= l). 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. --=20 balbi --+g7M9IMkV8truYOl Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.15 (GNU/Linux) iQIcBAEBAgAGBQJSszljAAoJEIaOsuA1yqREtgsP/1WvRak84V4bEBUj0U5HHlIx NS8+0pCNsRInkUB0lE9RlmxUoy5wUG93Ya54d3B1mwpi5ELxO9ypj+vjL4zZhfdG f3/ltNclqcZvIHViUkEIWZNTPHEMR7EyEeJIzeDIUsDxwoYOvmecIpF0ESLixgXc Ae2EWQ6w39nJRvLsRT8WnzCewvQ/Q2P88jAN87QWAcnw3p4cuxdMMirhe0ShXn80 MLW4oOPvhIYQpsrjqEa4eKzInXaUvmqXoRUB7hXpLB1vwxUpxfjiMo3XJg0kvzqC beMefSJUfIZiLov9ZMprGCuOynlH65hNaaTLPcI9bT+0IIlsWZKvZdBZM5sMLTbN 68Auywnds/ulskm8pOXzN09SpQB4Z1x6BnsCJpoemelPT9B04f4bCUU0ws0KwmeM oA0PeYmvKCfx5KPezxpXLoMTvnzVYF5YKBwdTHS1/Dq0XlaIOzGf+yuH0B3kulYw G6xfbbpu59rcAdEGkg/nYEvSJh9C78BZeVMbgtFsatcu/iom9FD8w3X6t24IA21E s8Ffitm92Z78MA7Gdn4O32nT8ssg2SKcNHnhqyNuBPK+kCZ+Hkn73UIuQp8oHxPh mFYXznNa3bqKnlDAwCQQo3ohBuvqsl069YI9qBY7a9CS9Q8v/B6Dp3y49ZMKAnMf m1U7f8WuqmtkRbBiQTb5 =Ly0q -----END PGP SIGNATURE----- --+g7M9IMkV8truYOl--