From mboxrd@z Thu Jan  1 00:00:00 1970
From: Stefan Roese <sr@denx.de>
Subject: i2c-i801 / SMBus timeouts on BayTrail board (U-Boot)
Date: Fri, 24 Jun 2016 13:57:21 +0200
Message-ID: <576D2021.4030808@denx.de>
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Cc: Mika Westerberg <mika.westerberg@linux.intel.com>, Jean Delvare <jdelvare@suse.com>, Jarkko Nikula <jarkko.nikula@linux.intel.com>, "Chew, Kean ho" <kean.ho.chew@intel.com>

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?

Thanks,
Stefan