[Nut-upsuser] Call for testing: removal of usb_set_altinterface() call

Charles Lepple clepple at gmail.com
Sat Aug 16 21:25:58 UTC 2014

If you have a USB UPS, and can rebuild NUT from source (tarball or Git), please read on.

I was trying to fix a problem specific to OS X and Tripp Lite UPSes, but it turns out that the redundant call to usb_set_altinterface(0) is right in the middle of the common NUT USB driver code, affecting pretty much any USB UPS that we support. So I would like to get a little additional testing before merging this. (Thanks to Steve Ballantyne for testing this on a different Tripp Lite model.)

Basically, this call to usb_set_altinterface() should not be needed (alternate interfaces are not often implemented in USB), but it appears that OS X might be sending this control message internally, and the extra call in the NUT source causes problems. Rather than rip it out completely, I made it configurable, just in case someone runs across an UPS that needs the old behavior.

The full branch is visible here: https://github.com/networkupstools/nut/compare/issue_138_altinterface_value

A few other fixes and reorganizations crept into this patch, but they are either just reorganization (08c721d...) or a workaround for the *.orig files that patch typically leaves behind (4fc6f73...).


When you test, it would be best to unplug and re-plug the UPS USB connection so that we are not relying on any previous USB setup. Please indicate your OS and UPS type when testing.


Charles Lepple
clepple at gmail

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