fcp handling

[Manfred W. <e95...@st...>]

I still have not tested the new fcp-functions, but I had a look at the
code and I think I discovered a flaw, which might cause errors in some
situations, which are very difficult to locate.

If I understood the code correctly, then by issuing
raw1394_start_fcp_listen we tell the kernel to store the packets
arriving in a buffer array which is located in raw1394_handle. BTW: That
ist the same buffer which is used for iso packets, so it would probably
be advisable for people, who are listening for iso_packets _and_
fcp_frames, to allocate two seperate handles for those two purposes (I
think, that should be mentioned in a comment in raw1394.h).
If a new packet arrives before the first one was read completly by the
application, it would overwritten and the application either loses the
first one completly or it reads a mixture (which can in worst case be a
mixture fcp-commands, fcp-responses and iso-packets).

I am also not quit sure, if it was a good idea to mix up the reception
of fcp commands and responses into one handler, since an application
might be interested in only listening to either commands or responses
(of cource, if somebody wants to implement a fully AV/C-compliant unit,
he will have to handle both).

In that context I have another qestion:
If two application (or one application using two raw-handles) register
for listening at the FCP addresses, which buffer will be used? Or will
the kernel create two copies of that packet in both raw-handle-buffers?
I think that the kernel will do this, but I just wanted to ask, because
I was not sure, and studying the source-code is not easy...

greetings

Manfred Weihs