From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752103Ab2GECfq (ORCPT ); Wed, 4 Jul 2012 22:35:46 -0400 Received: from hqemgate03.nvidia.com ([216.228.121.140]:1072 "EHLO hqemgate03.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751418Ab2GECe4 (ORCPT ); Wed, 4 Jul 2012 22:34:56 -0400 X-PGP-Universal: processed; by hqnvupgp06.nvidia.com on Wed, 04 Jul 2012 19:34:56 -0700 Message-ID: <4FF4FDC0.8020405@nvidia.com> Date: Thu, 5 Jul 2012 11:36:48 +0900 From: Alex Courbot Organization: NVIDIA User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:13.0) Gecko/20120616 Thunderbird/13.0.1 MIME-Version: 1.0 To: Mark Brown CC: Sascha Hauer , Thierry Reding , "linux-tegra@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-fbdev@vger.kernel.org" Subject: Re: [PATCH] pwm-backlight: add regulator and GPIO support References: <1340976167-27298-1-git-send-email-acourbot@nvidia.com> <20120704104840.GJ24458@pengutronix.de> <4FF43692.2040805@nvidia.com> <20120704130056.GC30009@pengutronix.de> <4FF45DDF.9000306@nvidia.com> <20120704152451.GA7333@sirena.org.uk> In-Reply-To: <20120704152451.GA7333@sirena.org.uk> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/05/2012 12:24 AM, Mark Brown wrote: > On Thu, Jul 05, 2012 at 12:14:39AM +0900, Alex Courbot wrote: >> On Wed 04 Jul 2012 10:00:56 PM JST, Sascha Hauer wrote: > >>> Also please be aware that using a regulator in the pwm backlight will >>> instantly break all existing users. That's hardly your fault though. > >> Sorry, I don't see why. Could you elaborate on this? > > All existing machines will start failing during probe as they won't be > able to find the regulator - you should ideally make sure everyone in > mainline gets an appropriate regulator set up. Oh, that is a mistake of mine then. Driver probe should continue if no regulator is declared (but should fail if some other error occured). I want to maintain backward compatibility with current users of the driver, so regulator/gpio specification should be optional. Thanks for all the feedback people - I will come back with a new version that addresses the points highlighted and also allows power on/off sequences to be specified in the device tree. Alex.