From mboxrd@z Thu Jan 1 00:00:00 1970 From: Graeme Smecher Subject: Re: [PATCH] gpio: pca953x: Don't flip bits on PCA957x GPIO expanders when probing them. Date: Mon, 23 Sep 2013 09:36:39 -0400 Message-ID: <524043E7.2050803@threespeedlogic.com> References: <1379108508-19933-1-git-send-email-gsmecher@threespeedlogic.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from threespeedlogic.com ([75.98.167.93]:59517 "EHLO threespeedlogic.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753603Ab3IWNji (ORCPT ); Mon, 23 Sep 2013 09:39:38 -0400 In-Reply-To: Sender: linux-gpio-owner@vger.kernel.org List-Id: linux-gpio@vger.kernel.org To: Linus Walleij Cc: Haojian Zhuang , "linux-gpio@vger.kernel.org" , gregory.clement@free-electrons.com Hi, On 23/09/13 06:57 AM, Linus Walleij wrote: > On Fri, Sep 13, 2013 at 11:41 PM, Graeme Smecher > wrote: > >> The pca957x driver supports a handful of I2C GPIO expanders from NXP, Maxim, >> and TI. For the PCA9574 and PCA9575 devices only, the driver resets the GPIO >> level and direction in the pca957x_probe function. This seems like the wrong >> thing to do, since it can cause hardware bit twiddles during warm reboots when >> the chip state and reset values don't match. >> >> This kind of initialization is best left upstream (in a bootloader) or >> downstream (in userspace). It's also an inconsistency across devices supported >> by this driver. >> >> This patch is NOT boot-tested: the SoC I'm using is stuck on 2.6.37, and the >> patch doesn't apply trivially. >> >> Signed-off-by: Graeme Smecher >> Acked-by: Haojian Zhuang > Patch applied with Gregory's Tested-by tag! Thanks all! cheers, Graeme