From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gregory CLEMENT Subject: Re: Openblocks AX3-4 i2c bus lockup Date: Tue, 31 Dec 2013 12:08:56 +0100 Message-ID: <52C2A5C8.7040201@free-electrons.com> References: <20131221164151.GF20115@lunn.ch> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Andrew Lunn Cc: linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux ARM , iwamatsu-+mkmVskJBflAfugRpC6u6w@public.gmane.org, Thomas Petazzoni List-Id: linux-i2c@vger.kernel.org Hi Andrew, On 22/12/2013 00:06, Gregory CLEMENT wrote: > Hi Andrew, >=20 > I am away this weekend (Christmas with the first part of the family). >=20 > But I remember having few issue on i2c with the first AX3-4 I receive= d. With the second one (using a B0 steping CPU), I didn't remember havi= ng any issues. As I thought the first AX3-4 I > received was an early release I didn't paid more attention. The last = i2c patches I sent were tested on the AX3-4 CPU rev B. >=20 > Could you tell me what kind of command did you do to get your issues = ? Then I will try to reproduce it on Monday on both revision >=20 > Thanks, >=20 > Gregory Sorry to not have answered earlier but when I investigated it I found an unexpected issue. =46irst I wanted to be sure that there the issue was not introduce by a commit so reverted one by one the commits on the file drivers/i2c/busses/i2c-mv64xxx.c. I tested it on both version of the OpenBlock AX-4 (with CPU A0 and B0). After each commit the kernel continue to work on the B0 version as expected, but it was when I reverted the commit "i2c: mv64xxx: Add I2C Transaction Generator support" that it worked also on the A0 version. Then I had a look on the errata datasheet and I found issues that I missed when I worked on it. This issues were fixed in B0 version. The fix should be pretty simple: disabling the offload_enabled flag whe= n an A0 version of the CPU is used. For this there are 2 solutions: introducing a new compatible string or trying to detect the CPU stepping at runtime. I would prefer the second solution and I am lookin= g for a way to get this information. Thanks, Gregory >=20 > Le 21 d=E9c. 2013 17:43, "Andrew Lunn" > a =E9crit : >=20 > Hi Nobuhiro >=20 > You added I2C into the Openblocks AX3-4 device tree and the subno= de > for the RTC. Did you have any problems with I2C? I'm having lots = of > problems with my AX3-4 and i2c. I get i2c errors and the bus bein= g > locked and then the whole machine locks solid. >=20 > Gregory, did you test your I2C patches for 370/XP on an Openblock= s > AX3-4? >=20 > Thanks > Andrew >=20 > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel >=20 --=20 Gregory Clement, Free Electrons Kernel, drivers, real-time and embedded Linux development, consulting, training and support. http://free-electrons.com