From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vaibhav Hiremath Subject: Re: [PATCH-v3 07/11] i2c: pxa: enable/disable i2c module across msg xfer Date: Mon, 13 Jul 2015 22:11:07 +0530 Message-ID: <55A3EA23.8070009@linaro.org> References: <1436210695-19159-1-git-send-email-vaibhav.hiremath@linaro.org> <1436210695-19159-8-git-send-email-vaibhav.hiremath@linaro.org> <20150710082419.GE1528@katana> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20150710082419.GE1528@katana> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Wolfram Sang Cc: linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, robert.jarzmik-GANU6spQydw@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, Yi Zhang List-Id: devicetree@vger.kernel.org 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