From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756929Ab0CLJGr (ORCPT ); Fri, 12 Mar 2010 04:06:47 -0500 Received: from ns.penguin.cz ([84.21.108.25]:44238 "EHLO ns.penguin.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756603Ab0CLJGn (ORCPT ); Fri, 12 Mar 2010 04:06:43 -0500 Subject: Re: bit errors on spitz From: Stanislav Brabec To: Andy Green Cc: Eric Miao , dbaryshkov@gmail.com, Cyril Hrubis , arminlitzel@web.de, kernel list , Dirk@opfer-online.de, lenz@cs.wisc.edu, rpurdie@rpsys.net, linux-arm-kernel , Pavel Machek , thommycheck@gmail.com, zaurus-devel@www.linuxtogo.org, omegamoon@gmail.com In-Reply-To: <4B995EE1.1050609@warmcat.com> References: <20100305212708.GC21773@elf.ucw.cz> <20100308072858.GA29939@atrey.karlin.mff.cuni.cz> <20100308082530.GA1982@atrey.karlin.mff.cuni.cz> <4B98EF5D.5000609@warmcat.com> <1268322155.3990.114.camel@hammer.suse.cz> <4B995EE1.1050609@warmcat.com> Content-Type: text/plain; charset="ISO-8859-2" Date: Fri, 12 Mar 2010 10:07:04 +0100 Message-ID: <1268384824.4963.35.camel@utx.utx.cz> Mime-Version: 1.0 X-Mailer: Evolution 2.28.2 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Andy Green wrote: > On 03/11/10 15:42, Somebody in the thread at some point said: > > Andy Green wrote: > > > >> I saw very similar failures for a long time on our iMX31 based device. > >> Eventually I found a Freescale errata where the RAM inside the USB2 > >> macrocell started to make single bit errors below 1.38V Vcore; ours was > >> 1.4V at that time but dipped on CPU load. > > > > Good tip. It seems that nobody ported driver for the voltage control > > chip ISL6271 from 2.4 kernel, and bootloader probably does not set > > correct values. > Unless there's more to it in the way the zaurus using it that regulator > isn't programmable digitally. OOPS, I made a mistake and linked ISL6721 instead of ISL6271 there. Now it is fixed: http://www.penguin.cz/~utx/zaurus/datasheets/power/XScale/ISL6271A.pdf This one has I2C. It is connected to GPIO 3 (PWR_SCL) and GPIO 4 (PWR_SDA). It is visible between the black plastic and the large circular coil: http://www.penguin.cz/~utx/zaurus/teardown#pcbt > Reading about your CF Card WLAN related issues they suck down a good > amount of power when their radio is up, I would definitely suggest > monitoring with a 'scope the various rails (Vcore, RAM and whatever it > is the CF Card is powered by) while putting it under load. I guess that Zaurus has a good power design and that voltage should be constant enough. CF has a dedicated step down (plus 2.8V power detector (Why so low, if CF standard requres more?)), HDD has a dedicated step up/down. USB has dedicated step up. Companion chips use dedicated 3.3V step down. Audio uses dedicated linear regulator. CPU has several dedicated step downs, CPU 3.3V uses step-up to 5V and then down to 3.3V (which is shared only with IOPORT). Nearest common point between CF card power and CPU power is the battery. ________________________________________________________________________ Stanislav Brabec http://www.penguin.cz/~utx/zaurus