Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757251AbYFIRIs (ORCPT ); Mon, 9 Jun 2008 13:08:48 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752577AbYFIRIk (ORCPT ); Mon, 9 Jun 2008 13:08:40 -0400 Received: from mail.gmx.net ([213.165.64.20]:38943 "HELO mail.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751522AbYFIRIk (ORCPT ); Mon, 9 Jun 2008 13:08:40 -0400 X-Authenticated: #20450766 X-Provags-ID: V01U2FsdGVkX1+dLo94OPydui1UBb2N9cGGR3MLsfK6SqhN6MyEud 0Gra2m+joEYMVg Date: Mon, 9 Jun 2008 19:09:00 +0200 (CEST) From: Guennadi Liakhovetski To: Mark Brown cc: David Brownell , linux-kernel@vger.kernel.org Subject: Re: [RFC] generic GPIO parameter API In-Reply-To: <20080609165438.GE17278@sirena.org.uk> Message-ID: References: <200806052229.37143.david-b@pacbell.net> <20080609165438.GE17278@sirena.org.uk> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Y-GMX-Trusted: 0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1849 Lines: 40 On Mon, 9 Jun 2008, Mark Brown wrote: > On Mon, Jun 09, 2008 at 06:23:50PM +0200, Guennadi Liakhovetski wrote: > > On Thu, 5 Jun 2008, David Brownell wrote: > > > On Monday 02 June 2008, Guennadi Liakhovetski wrote: > > > > > as far as I understand, the current GPIO API only presents very basic GPIO > > > > functionality: direction and level reading and writing. Whereas many GPIO > > > > controllers have many further configurable parameters: pull-ups and > > > > pull-downs, drive strength, slew rate, etc. > > > > Not at all how I'd describe it. Those omitted mechanisms are part > > > of pin configuration, in the same way as function multiplexing is. > > > (That is, assigning a given pin for use as a GPIO, vs hooking it up > > > to an I2C, MMC, SPI, LCD, I2S, or memory controller.) > > > Yes, on the one hand you're right, this belongs to pin-configuration. But, > > otoh, will anyone ever want to change these parameters on non-generic > > pins? And should this be allowed? Whereas for GPIOs it clearly makes a > > They do get configured like that - for example, most I2S devices are > able to operate as both clock masters and clock slaves. Often this > accomplished (at least in part) by configuring the relevant pins as > inputs or outputs. The primary purpose of the GPIO-parameter proposal was to allow to configure these parameters from the user-space over sysfs by extending the gpio-sysfs patch. And I2S master / slave operation should not be switchable over sysfs, should it? Thanks Guennadi --- Guennadi Liakhovetski, Ph.D. Freelance Open-Source Software Developer -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/