From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kefeng Wang Subject: Re: question about i2c-designware Date: Fri, 10 Jul 2015 12:11:38 +0800 Message-ID: <559F45FA.8060801@huawei.com> References: <559E37D7.6040103@huawei.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <559E37D7.6040103-hv44wF8Li93QT0dZR+AlfA@public.gmane.org> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Cc: Wolfram Sang , Alexey Brodkin , Ding Tianhong , "Guohanjun (Hanjun Guo)" , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" List-Id: linux-i2c@vger.kernel.org + linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org On 2015-07-09 16:59, Kefeng Wang wrote: > Hi all, > > We met a issue when use Synopsys DesignWare I2C. The SDA will keep low level and never go back to the high level > if both i2c controllers simultaneously access the same i2c device(rtc), then both two i2c controllers can't send any data. > we try to reset the rtc, but not working. After reset the i2c controller, the SDA goes back to the high state and we > can get time from rtc again. > > The scenario is as follows, any advice will be appreciated. > > OS 1 | OS 2 > | > +--------------+----------|--------------+ > | | | | > | +---------|----+-----|---------+ | > | | | | | | | > ---------------- ------ | ----------------- > |i2c controller1| | rtc| | |i2c controller2| > ---------------- ------ | ----------------- > | > note: > 1) i2c controller1 and controller2 use same IP. > 2) OS1 use v3.19 and OS2 use 2.6 > > Thanks > Kefeng >