i2c clock running at 16Khz

Jean Delvare khali at linux-fr.org
Tue Jan 25 20:59:14 CET 2005

Hi Oliver,

> > BTW, may I ask how you did measure the frequency?
> I hooked an oscilloscope to the clock and data pins.

Impressive :) I wish I had the necessary hardware to do so.

> > May I know the SMBus speed (or rather slowness) is so important to
> > you?
> The 3rd party board I am trying to use does not seem to like the
> slower  clock rate.

Strange, usually most chips are fine with that (which is why they chose
it, I guess).

OK, you may try to apply the attached patch to your kernel tree. It
attempts to change a PCI configuration bit which *might* switch the
SMBus speed from 16kHz to 64kHz. I am not able to verify whether it
works or not since I do not have an oscilloscope, and the i2c-viapro is
poll-based so measuring performance from userspace doesn't help (the
poll delay dominates the SMBus speed by a huge factor). Also it might
not work for all VIA chips, I have no datasheets, I can't say. You tell
me if it works for you :)

Jean Delvare
-------------- next part --------------
An embedded and charset-unspecified text was scrubbed...
Name: linux-2.6.11-rc1-i2c-viapro-speed.diff
URL: <http://lists.lm-sensors.org/pipermail/lm-sensors/attachments/20050125/4511ea95/attachment.ksh>

More information about the lm-sensors mailing list