Data block transactions fail on i2c-i801 controller?

David Knierim david_knierim at
Tue Sep 21 16:58:37 CEST 2004

The logs were pretty large, so we placed them on the web:

dmesg_noblock - block data disabled
dmesg_withblock - block data enabled


-----Original Message-----
From: "Mark M. Hoffman" <mhoffman at>
Sent: Sep 20, 2004 5:22 PM
To: David Knierim <david_knierim at>
Subject: Re: Data block transactions fail on i2c-i801 controller?

Hi David:

* David Knierim <david_knierim at> [2004-09-20 16:40:33 -0400]:
> Hi,
>    I'm working with server based on Intel 7520 (Lindenhurst) chipset.   This uses the i2c-i801 bus driver.   An lm93 is attached to this bus.    If I load the lm93 in it's default mode, which "allows SMBus block data transactions if the host supports them", it takes a long time for sensors to run.   This is the output of "time":
> real    0m10.901s
> user    0m0.010s
> sys     0m0.010s
> If the lm93 is loaded with it's disable_block mode, which disables data block transactions, the operation is much faster:
> real    0m1.261s
> user    0m0.010s
> sys     0m0.010s
> In both cases, there are no errors logged to dmesg or /var/log/messages.   The output is correct in both cases.   The data block transaction mode just takes a lot longer to complete.
> Any ideas??

Please uncomment line 42 "#define DEBUG" and rebuild, reinstall,
and try again.  Now you should get some log messages... please
send those here; hopefully the original authors (Phil & MDS) can
have a look as well.


Mark M. Hoffman
mhoffman at

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