From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gregory CLEMENT Subject: Re: [PATCH] gpio: pca953x: Don't flip bits on PCA957x GPIO expanders when probing them. Date: Fri, 20 Sep 2013 22:37:47 +0200 Message-ID: <523CB21B.207@free-electrons.com> References: <1379108508-19933-1-git-send-email-gsmecher@threespeedlogic.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from top.free-electrons.com ([176.31.233.9]:49214 "EHLO mail.free-electrons.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752055Ab3ITUh5 (ORCPT ); Fri, 20 Sep 2013 16:37:57 -0400 In-Reply-To: Sender: linux-gpio-owner@vger.kernel.org List-Id: linux-gpio@vger.kernel.org To: Linus Walleij Cc: Graeme Smecher , Haojian Zhuang , "linux-gpio@vger.kernel.org" Hi Linus, On 20/09/2013 22:24, 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 > > Looks like you're deleting code from Gregory CLEMENT, > Gregory what do you say about this? Thanks to point me this patch, I didn't have noticed it. The code being removed is mine because I change it to take care of the multiple bankd. I didn't change the functionality. The original code was from Haojian Zhuang so as he gave his acked-by it should be fine. However could you wait for until the end of this week end, to let me test it on a real hardware? Thanks, Gregory -- Gregory Clement, Free Electrons Kernel, drivers, real-time and embedded Linux development, consulting, training and support. http://free-electrons.com