Nut upsdev - Aug 2014 - Call for testing: removal of usb_set_altinterface() call

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...).

https://github.com/networkupstools/nut/commit/08c721d67ca232d52c6b7d5e67182d56009f8cc7
https://github.com/networkupstools/nut/commit/4fc6f738478e60be9d306cff9eb0f1e38cb53d78

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.

Thanks,

-- 
Charles Lepple
clepple at gmail


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Let's try the dev list.

Anyone have a spare USB UPS they can test against? The fix is for Tripp Lite and
OS X, but I'm looking for other data points because the code is common to
nearly *all* of the USB drivers, and could break them.

Thanks!

On Aug 16, 2014, at 5:25 PM, Charles Lepple <clepple at gmail.com> wrote:
> 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...).
> 
>
https://github.com/networkupstools/nut/commit/08c721d67ca232d52c6b7d5e67182d56009f8cc7
>
https://github.com/networkupstools/nut/commit/4fc6f738478e60be9d306cff9eb0f1e38cb53d78
> 
> 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.
> 
> Thanks,
> 
> -- 
> Charles Lepple
> clepple at gmail
> 
> 
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