From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jean Delvare Subject: Re: i2c-i801 / SMBus timeouts on BayTrail board (U-Boot) Date: Fri, 24 Jun 2016 15:38:42 +0200 Message-ID: <1466775522.8139.3.camel@chaos.suse> References: <576D2021.4030808@denx.de> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: Received: from smtp.nue.novell.com ([195.135.221.5]:44955 "EHLO smtp.nue.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751454AbcFXNiz (ORCPT ); Fri, 24 Jun 2016 09:38:55 -0400 In-Reply-To: <576D2021.4030808@denx.de> Sender: linux-i2c-owner@vger.kernel.org List-Id: linux-i2c@vger.kernel.org To: Stefan Roese Cc: linux-i2c@vger.kernel.org, Mika Westerberg , Jarkko Nikula , "Chew, Kean ho" Hi Stefan, 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? * Did you try comparing the PCI configuration space of the SMBus device between original BIOS boot (working) and U-Boot boot (not working)? -- Jean Delvare SUSE L3 Support