From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755539Ab3ETJ7k (ORCPT ); Mon, 20 May 2013 05:59:40 -0400 Received: from cam-admin0.cambridge.arm.com ([217.140.96.50]:45029 "EHLO cam-admin0.cambridge.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754554Ab3ETJ7h (ORCPT ); Mon, 20 May 2013 05:59:37 -0400 Date: Mon, 20 May 2013 10:58:57 +0100 From: Will Deacon To: Andy Shevchenko Cc: Vinod Koul , "djbw@fb.com" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "andriy.shevchenko@linux.intel.com" , "viresh.kumar@linaro.org" Subject: Re: dmatest regression in 3.10-rc1 Message-ID: <20130520095857.GI31359@mudshark.cambridge.arm.com> References: <20130515152803.GL23869@mudshark.cambridge.arm.com> <20130516153553.GI11706@mudshark.cambridge.arm.com> <20130517123423.GR14863@intel.com> <20130517141857.GM23112@mudshark.cambridge.arm.com> <1369036354.29283.115.camel@smile> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1369036354.29283.115.camel@smile> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Andy, On Mon, May 20, 2013 at 08:52:34AM +0100, Andy Shevchenko wrote: > On Fri, 2013-05-17 at 15:18 +0100, Will Deacon wrote: > > On Fri, May 17, 2013 at 01:34:23PM +0100, Vinod Koul wrote: > > > On Thu, May 16, 2013 at 04:35:53PM +0100, Will Deacon wrote: > > > > Right, so I think I understand what's causing this, but I'll leave it to > > > > Andriy to suggest a fix. > > Thanks for the report. > > Unfortunately neither me nor other guys in the team could not reproduce > mentioned issue on our hardware. > Nevertheless I will try to allocate time and suggest possible fix if any > comes to my mind. So, your testing and analysis is appreciated. Sure. They way I trigger it is to unload the module whilst the DMA is ongoing (I'm using a software model, so I can make the DMA nice and slow -- I guess you could try using some large buffers). My script (I just run from busybox) is: #!/bin/sh mount proc -t proc /proc mount sysfs -t sysfs /sys mount debugfs -t debugfs /sys/kernel/debug echo 9 > /proc/sysrq-trigger modprobe dmatest echo 8 > /sys/kernel/debug/dmatest/iterations echo 8 > /sys/kernel/debug/dmatest/threads_per_chan echo 131072 > /sys/kernel/debug/dmatest/test_buf_size echo 1 > /sys/kernel/debug/dmatest/run modprobe -r dmatest Will