From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stefan Roese Subject: Re: i2c-i801 / SMBus timeouts on BayTrail board (U-Boot) Date: Fri, 24 Jun 2016 16:33:42 +0200 Message-ID: <576D44C6.4030702@denx.de> References: <576D2021.4030808@denx.de> <1466775522.8139.3.camel@chaos.suse> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mx2.mailbox.org ([80.241.60.215]:54808 "EHLO mx2.mailbox.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750988AbcFXOdx (ORCPT ); Fri, 24 Jun 2016 10:33:53 -0400 In-Reply-To: <1466775522.8139.3.camel@chaos.suse> Sender: linux-i2c-owner@vger.kernel.org List-Id: linux-i2c@vger.kernel.org To: Jean Delvare Cc: linux-i2c@vger.kernel.org, Mika Westerberg , Jarkko Nikula , "Chew, Kean ho" Hi Jean, On 24.06.2016 15:38, Jean Delvare wrote: > On ven., 2016-06-24 at 13:57 +0200, Stefan Roese wrote: >> Hi, >> >> I'm currently trying to use the SMBus on a congatec BayTrail board. >> This works just fine when booting via the original BIOS. But when I >> boot into Linux using U-Boot as bootloader, I get the following >> errors: >> >> [ 81.877121] i801_smbus 0000:00:1f.3: Transaction timeout >> [ 81.879228] i801_smbus 0000:00:1f.3: Failed terminating the transaction >> [ 81.879320] i801_smbus 0000:00:1f.3: SMBus is busy, can't use it! >> [ 81.879373] i801_smbus 0000:00:1f.3: SMBus is busy, can't use it! >> [ 81.879421] i801_smbus 0000:00:1f.3: SMBus is busy, can't use it! >> [ 81.879496] i801_smbus 0000:00:1f.3: SMBus is busy, can't use it! >> ... >> >> I checked with an oscilloscope and the SMBus clock is not toggling >> at all in this case. My feeling is, that some basic setup is missing >> in this non-BIOS case. Like some clock enabling. Does anyone of you >> have some idea here? > > No immediate idea, sorry. Two ideas: > > * Is this problem specific to Baytrail systems, or does i2c-i801 fail on > all U-Boot systems? I only have BayTrail systems right now. > * Did you try comparing the PCI configuration space of the SMBus device > between original BIOS boot (working) and U-Boot boot (not working)? The issue seems to be solved just a few minutes ago. As it seems a pin-mux configuration was missing for the SMBus pins. Now the bus can be scanned in Linux without any issues. Thanks, Stefan