[avrdude-dev] [bug #34339] back to back avrdude commands fail on dragon_isp on Ubuntu 10.10

[Joerg Wunsch]

Update of bug #34339 (project avrdude):

                  Status:                    None => Wont Fix               
             Assigned to:                    None => joerg_wunsch           

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Follow-up Comment #1:

This is not an AVRDUDE issue but an operating system one.  It
is completely independent of whether there's a usb_reset()
being done; even on FreeBSD, you'll observe the same behaviour.
It's due to the programming tool itself disconnecting from the
bus, and reconnecting, so your OS'es entire enumeration
process has to be passed, before you can use it again.

Adding any kind of delay inside AVRDUDE would simply annoy
those who don't see their shell prompt back again after
programming, for no obvious reason.  Also, _any_ delay value
could be too low or too high, and your OS'es delay value can
be completely wrong for the next OS, or even the next version
of your OS.  This is nothing but speculation.  I'm not sure
whether retrying the USB open will really work well enough
in all situations.  I probably wouldn't resist applying a
well-tested patch for that if it proves to work on all
supported operating systems (Linux, Win32, FreeBSD, MacOS X,
maybe Solaris though I'm not sure about the state of USB
support there).

As it's not an AVRDUDE issue, it should be solved outside, in
your case probably in the Arduino IDE itself.  It's responsible
for adding a sufficient delay between two calls.

Another option for Arduino would be that they use the AVRDUDE
library rather than the command, within a single AVRDUDE
programming session, so no USB reconnect is needed.  This
library is currently not being installed into the target system,
simply because it's not clear whether the library/UI 
separation works well enough for a real application, so this
would require a close cooperation of the Arduino and the
AVRDUDE developers.

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