Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751929AbbGMQlR (ORCPT ); Mon, 13 Jul 2015 12:41:17 -0400 Received: from mail-pa0-f42.google.com ([209.85.220.42]:36632 "EHLO mail-pa0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750919AbbGMQlO (ORCPT ); Mon, 13 Jul 2015 12:41:14 -0400 Message-ID: <55A3EA23.8070009@linaro.org> Date: Mon, 13 Jul 2015 22:11:07 +0530 From: Vaibhav Hiremath User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: Wolfram Sang CC: linux-i2c@vger.kernel.org, linux-arm-kernel@lists.infradead.org, robert.jarzmik@free.fr, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, robh+dt@kernel.org, Yi Zhang Subject: Re: [PATCH-v3 07/11] i2c: pxa: enable/disable i2c module across msg xfer References: <1436210695-19159-1-git-send-email-vaibhav.hiremath@linaro.org> <1436210695-19159-8-git-send-email-vaibhav.hiremath@linaro.org> <20150710082419.GE1528@katana> In-Reply-To: <20150710082419.GE1528@katana> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1380 Lines: 41 On Friday 10 July 2015 01:54 PM, Wolfram Sang wrote: > On Tue, Jul 07, 2015 at 12:54:51AM +0530, Vaibhav Hiremath wrote: >> From: Yi Zhang >> >> Enable i2c module/unit before transmission and disable when it finishes. >> >> why? >> It's because the i2c bus may be distrubed if the slave device, >> typically a touch, powers on. >> >> As we do not want to break slave mode support, this patch introduces >> DT property to control disable of the I2C module after xfer in master mode >> of operation. >> >> i2c-disable-after-xfer : If set, driver will disable I2C module after msg xfer > > Hmm, I am not sure this property fits into the "describing hardware" > category. And we can't make the below behaviour default, because the > udelay(100) will cause quite some latency. > >> Sorry for delayed response, I thought I responded to this, but when I was preparing for V4, realized it that I did not :) Yes, I agree that, this doesn't look like HW description. But I could not find any other mechanism to handle this. And also during V1 discussion, I did not get any objection to this approach. Thanks, Vaibhav -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/