From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tony Lindgren Subject: Re: [PATCH v3 2/4] i2c: omap: implement workaround for handling invalid BB-bit values Date: Mon, 24 Nov 2014 11:25:17 -0800 Message-ID: <20141124192517.GE2757@atomide.com> References: <1416518925-20679-1-git-send-email-al.kochet@gmail.com> <1416685634-5864-1-git-send-email-al.kochet@gmail.com> <1416685634-5864-3-git-send-email-al.kochet@gmail.com> <20141124191023.GG25712@saruman> <20141124191347.GA26751@katana> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20141124191347.GA26751@katana> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Wolfram Sang Cc: Felipe Balbi , Kevin Hilman , Alexander Kochetkov , linux-omap , linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, lkml List-Id: linux-i2c@vger.kernel.org * Wolfram Sang [141124 11:14]: > On Mon, Nov 24, 2014 at 01:10:23PM -0600, Felipe Balbi wrote: > > On Mon, Nov 24, 2014 at 11:08:48AM -0800, Kevin Hilman wrote: > > > On Sat, Nov 22, 2014 at 11:47 AM, Alexander Kochetkov > > > wrote: > > > > In a multimaster environment, after IP software reset, BB-bit value doesn't > > > > correspond to the current bus state. It may happen what BB-bit will be 0, > > > > while the bus is busy due to another I2C master activity. > > > > > > > > Any transfer started when BB=0 and bus is busy wouldn't be completed by IP > > > > and results in controller timeout. More over, in some cases IP could > > > > interrupt another master's transfer and corrupt data on wire. > > > > > > > > The commit implement method allowing to prevent IP from entering into > > > > "controller timeout" state and from "data corruption" state. > > > > > > > > The one drawback is the need to wait for 10ms before the first transfer. > > > > > > > > Tested on Beagleboard XM C. > > > > Tested on BBB and AM437x Starter Kit by Felipe Balbi. > > > > > > > > Signed-off-by: Alexander Kochetkov > > > > Tested-by: Felipe Balbi > > > > Reviewed-by: Felipe Balbi > > > > > > This patch recently hit linux-next (as commit 903c3859f77f) and boot > > > breakage[1] in next-20141124 on OMAP3530 Beagle and Overo/Tobi boards > > > was bisected down to this commit. > > > > > > Kevin > > > > > > [1] http://status.armcloud.us/boot/?next-20141124&omap > > > > btw, based on Kevin's boot test, only OMAP3530 is failing. > > OK, giving Alexander some time for a fix. If it can't be found, I'll > revert this patch. Thanks! I can confirm reverting it fixes things for me as well thanks. Regards, Tony