[Nut-upsdev] Bug#462468: nut: megatec_usb ups not detected since 2.2.1 update anymore

[Arjen de Korte]

> that is the case for usbhid-ups: the various functions that accept a
> TIMEOUT use 4 sec...

That is still incorrect and I want to change that in the not so distant
future (time permitting). Unfortunately, that also requires some changes
in the hid_ups_walk() function that are not so trivial. Basically, what I
would like to do is to send a command, read the reply with a timeout of
say about a second. If we have a reply at that time, we process it and
send the next request. If we get EAGAIN, we just wait for the next round
until a 5 second timer has elapsed since sending the command.

> And 1 second can be too short.

If you handle the EAGAIN return code properly, it becomes irrelevant.

>> The problem here is that none of the subdrivers in 'megatec_usb.c' in
>> nut-2.2.1 handle the return codes from the libusb functions properly. By
>> sending the EAGAIN error code, they clearly indicate that the command
>> needs to be retried, instead of declaring it a failure. This might be
>> handled a little better from r1211 onwards, which added a the
>> possibility
>> to reconnect. I'm not sure if reconnecting is the proper way to handle
>> this though. It might be better to just retry the command the next time.
>
> has this been backported to Testing?

I hope not, because there are still a couple of loose ends in the trunk,
so I wouldn't consider this code stable enough for Testing.

Best regards, Arjen
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