From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ppsw-50.csi.cam.ac.uk ([131.111.8.150]:50710 "EHLO ppsw-50.csi.cam.ac.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751392Ab1JLPlb (ORCPT ); Wed, 12 Oct 2011 11:41:31 -0400 Message-ID: <4E95B52B.1080409@cam.ac.uk> Date: Wed, 12 Oct 2011 16:41:31 +0100 From: Jonathan Cameron MIME-Version: 1.0 To: Mark Brown CC: Arnd Bergmann , Zoltan Devai , Linus Walleij , linux-arm-kernel@lists.infradead.org, linux-iio@vger.kernel.org Subject: Re: [PATCH 4/9] ARM: SPMP8000: Add ADC driver References: <1318178172-7965-1-git-send-email-zoss@devai.org> <201110111617.52061.arnd@arndb.de> <20111011144005.GI3471@opensource.wolfsonmicro.com> <201110111724.48069.arnd@arndb.de> <20111012144251.GM3647@opensource.wolfsonmicro.com> In-Reply-To: <20111012144251.GM3647@opensource.wolfsonmicro.com> Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-iio-owner@vger.kernel.org List-Id: linux-iio@vger.kernel.org On 10/12/11 15:42, Mark Brown wrote: > On Tue, Oct 11, 2011 at 05:24:47PM +0200, Arnd Bergmann wrote: >> On Tuesday 11 October 2011, Mark Brown wrote: > >>> I'm not sure that IIO isn't the kernel subsystem we're looking for here >>> - as I keep saying when this comes up it's just representing bare DACs >>> and ADCs pretty directly which looks like a generic subsystem to me. > >> Possible, yes. Until now, IIO is a subsystem for user-level access >> not for kernel access though, so it's not the right place yet. >> If we decide to let IIO handle all ADC input, do you think it would >> also be the right place to do PWM output, rather than having a >> separate subsystem for that? > > Off the top of my head I'd expect PWM to be a separate thing which could > optionally synthesize stuff onto an IIO device (bitbanging the PWM > essentially). The specialized PWM stuff tends to be "output this steady > state for an indefinite period" type interface rather than "here's a > batch of samples, output them". Same can be true of dds chips, with the addition that they often have gpio type switching between a set of predefined frequencies (FM basically). + weird waveform choices sometimes.