[lm-sensors] sensors-detect: probing i2c sensors racy?

[Forest Bond]

Hi,

On Wed, Dec 09, 2009 at 10:32:25AM -0500, Forest Bond wrote:
> I am seeing a situation where sensors-detect fails to find sensors in a single
> run due to an apparent race condition.  It looks like it loads the i2c-* modules
> and then tries to open /dev/i2c-0 for probing, but it fails to open
> successfully.  My sense is that the device is not fully initialize and ready for
> opening immediately following the modprobe calls, but sensors-detect does not
> wait for initialization to complete.  I'm not sure what should be happening.  It
> seems sensible that modprobe would not return until the device is initialized.
> 
> Running sensors-detect again correctly probes the hardware because the i2c bus
> is fully initialized at that point.
> 
> I don't know anything about i2c, so I hope the language I'm using to describe
> this situation is reasonable.
> 
> I've attached the output from sensors-detect for the first (failed) run and the
> second (successful) run.

FWIW, this issue is also affecting the same hardware:

https://bugs.launchpad.net/ubuntu/+source/lm-sensors-3/+bug/458811

sensors-detect issue was noted while testing with acpi=off to avoid the resource
conflict.  Maybe the two issues are related.

-Forest
-- 
Forest Bond
http://www.alittletooquiet.net
http://www.pytagsfs.org
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