tree 19861b5b1213d6f0e9571f6c640095f7d74b642c
parent e81cbebdfc384f9c2ae91225f16ef994118e5e2c
author Clemens Ladisch <clemens@ladisch.de> 1298449660 +0100
committer Stefan Richter <stefanr@s5r6.in-berlin.de> 1298729464 +0100

firewire: ohci: prevent starting of iso contexts with empty queue

If a misguided program tried to start an isochronous context before it
has queued any packets, the call would appear to succeed, but the
context would not actually go into the running state, and the OHCI
controller would then raise an unrecoverableError interrupt because the
first Z value is zero and thus invalid.  The driver logs such errors,
but there is no mechanism to report this back to the program.

Add an explicit check so that this error can be returned synchronously.

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