Incorrect error handling when device reconnected

[Tim Waugh]

If a USB device is forced to reconnect for some reason, the error handling in prnt/backend/hp.c is incorrect. The USB channel it has opened will have become invalidated, although the printer device itself is perfectly happy.

One example of this occurring is here:
  https://bugzilla.redhat.com/show_bug.cgi?id=515481

Attached is a patch to spot this situation and abort.

[David Suffield (david-suffield)]

Thanks for the patch but this patch masks the real problem. The device-id request should fail when the current USB bus/device number is no longer valid.

Based on the syslog feedback at https://bugzilla.redhat.com/show_bug.cgi?id=515481 I removed the PS A420 retry in the hpmud device-id code. This change will allow the device-id to fail and return with error set.

BTW a spurious USB reset is usually caused by noise over the USB cable. Make sure the cable is USB 2.0 certified. USB 1.1 cables are problematic with USB 2.0 devices.

[Ani Balakrishnan (anib)]

Thanks David for the feedback.
 As per the above feedback by David , the issue is already resolved and we are not incorporating the patch given by Tim.