his garbage in the self ID buffer made firewire-core ignore all of the
self ID data, and thus prevented the Linux bus manager from correcting
the problem.  Furthermore, because the bus reset handling was aborted
completely, asynchronous transfers would be no longer handled correctly,
and fw_run_transaction() would hang until the next bus reset.

To fix this, make the detection of inconsistent self IDs more
discriminating:  If the invalid data in the self ID buffer looks like
a cycle start packet, we can assume that the previous data in the buffer
is correctly received self ID information, and process it normally.

(We inspect only the first quadlet of the cycle start packet, because
this value is different enough from any valid self ID quadlet, and many
controllers do not store the cycle start packet in five quadlets because
they expect self ID data to have an even number of quadlets.)

This bug has been observed when a bus-powered DesktopKonnekt6 is
switched off with its power button.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
8