From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755176Ab0JESHP (ORCPT ); Tue, 5 Oct 2010 14:07:15 -0400 Received: from mail-iw0-f174.google.com ([209.85.214.174]:41517 "EHLO mail-iw0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753416Ab0JESHN (ORCPT ); Tue, 5 Oct 2010 14:07:13 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=i/BRdajV1AYDgGcB10Xc9al5AUY9zwMYelypjXRAHRP2iBmZmrPZSlllV98r+fNRwY ZfcaI4DHX1r09b/veYP9M2HToTayNwWgsw2Gy7WF4qWGG5LJV7uEIPkGhdth9u4QzW4S S+vg3NGy8OwWAL/z2OkY8qH4/w9nWFlm5+V60= Date: Tue, 5 Oct 2010 11:07:03 -0700 From: Dmitry Torokhov To: Mark Brown Cc: Igor Grinberg , Marek Vasut , linux-arm-kernel@lists.infradead.org, vapier@gentoo.org, khilman@deeprootsystems.com, linux-kernel@vger.kernel.org, pavel@ucw.cz, linux-input@vger.kernel.org, eric.y.miao@gmail.com, akpm@linux-foundation.org Subject: Re: [PATCH v2] Input: Make ADS7846 independent on regulator Message-ID: <20101005180703.GD21399@core.coreip.homeip.net> References: <1280560182-7071-1-git-send-email-marek.vasut@gmail.com> <4C862EB3.4080006@compulab.co.il> <20100907125335.GD25830@sirena.org.uk> <201009091027.18176.marek.vasut@gmail.com> <20100909094120.GB1988@rakim.wolfsonmicro.main> <4CAACA63.6090202@compulab.co.il> <20101005161608.GD19730@core.coreip.homeip.net> <20101005164037.GA20555@opensource.wolfsonmicro.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20101005164037.GA20555@opensource.wolfsonmicro.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 05, 2010 at 09:40:38AM -0700, Mark Brown wrote: > On Tue, Oct 05, 2010 at 09:16:08AM -0700, Dmitry Torokhov wrote: > > On Tue, Oct 05, 2010 at 08:49:07AM +0200, Igor Grinberg wrote: > > > > You want each platform, that does not have a special regulated power supply > > > for the ads7846, to define a dummy regulator just to cope with that artificial > > > dependency of the device driver? > > > I think it is a waste and big code duplication in each platform > > > that does not have that special regulator. > > It's a pretty good fit for most current systems - with current hardware > you will normally have some software control for the vast majority of > the regulators on the board if you have regulator control at all since > that's the way PMICs have gone. Having a complete map of the regulator > usage in the system is useful since it allows us to do optimisations > like powering down idle regulators much more readily. > > > I tend to agree, however I think that original patch that simply ignored > > failures from regulator_get() is not the best option either. Can we have > > a flag in platform data indicating that the board does not employ a > > regulator? Then we could retain the hard failure in cases when we expect > > regulator to be present while allowing to continue on boards that do not > > have it. > > I really don't think it's a good idea to add this code to every single > regulator using driver - this seems like an enormous waste of time and > code complexity cost. I have suggested several times that we should > extend the dummy regulator mode so that boards can enable it from code > as well as users enable it from Kconfig, I'm not sure why everyone is so > keen on bodging this in drivers. It all depends on what instances you expect to encounted more often - drivers or boards without regulators... -- Dmitry