[mythtv-users] Why does the backend sometimes get my Firewire port wrong?

[Phil Bridges]

Sometimes when I'm watching LiveTV on a remote frontend through my
cable box's Firewire port (please no griping about LiveTV - this is
the only way to watch my non-ClearQAM channels in my bedroom), I'll
change the channel, and no video will display - I'll just get the
"There is an error displaying video" screen (or words to that effect).
 When I look at my backend logs, I get this message:

2008-11-02 05:29:18.511 TVRec(7): ASK_RECORDING 7 0 0 0
2008-11-02 05:29:18.599 TVRec(7): Changing from None to RecordingOnly
2008-11-02 05:29:18.600 TVRec(7): HW Tuner: 7->7
2008-11-02 05:29:18.600 LAVCInfo(), Error: Unable to get handle for port: -1
                        eno: Invalid argument (22)
2008-11-02 05:29:18.603 TVRec(7) Error: Failed to set channel to 876.
Reverting to kState_None
2008-11-02 05:29:18.603 TVRec(7): Changing from RecordingOnly to None

It appears that restarting the backend is the only way to reset what
Firewire port is being used - when I restart the backend and use the
Firewire input again, I get:

2008-11-02 05:32:30.205 LFireDev(001BDDFFFEF17BEB), Warning: No Input
in 1050 msec...
2008-11-02 05:32:30.206 LFireDev(001BDDFFFEF17BEB): ResetBus() -- begin
2008-11-02 05:32:30.208 LFireDev(001BDDFFFEF17BEB): ResetBus() -- end
2008-11-02 05:32:30.209 LFireDev(001BDDFFFEF17BEB): SignalReset(126->127)
2008-11-02 05:32:30.209 LFireDev(001BDDFFFEF17BEB):
SignalReset(126->127): Updating device list -- begin
2008-11-02 05:32:30.530 LFireDev(001BDDFFFEF17BEB):
SignalReset(126->127): Updating device list -- end
libiec61883 warning: iec61883_cmp_create_bcast_output: Failed to set
the oPCR[0] plug for node 63.
2008-11-02 05:32:30.646 LFireDev(001BDDFFFEF17BEB), Error: Bus Reset :
Failed to reconnect
2008-11-02 05:32:31.009 LFireDev(001BDDFFFEF17BEB), Warning: No Input
in 50 msec...
[snip]
2008-11-02 05:32:32.049 LFireDev(001BDDFFFEF17BEB), Warning: No Input
in 1050 msec...
2008-11-02 05:32:32.050 LFireDev(001BDDFFFEF17BEB): ResetBus() -- begin
2008-11-02 05:32:32.053 LFireDev(001BDDFFFEF17BEB): ResetBus() -- end
2008-11-02 05:32:32.054 LFireDev(001BDDFFFEF17BEB): SignalReset(127->128)
2008-11-02 05:32:32.054 LFireDev(001BDDFFFEF17BEB):
SignalReset(127->128): Updating device list -- begin
2008-11-02 05:32:32.062 LFireDev(001BDDFFFEF17BEB):
SignalReset(127->128): Updating device list -- end
2008-11-02 05:32:32.113 LFireDev(001BDDFFFEF17BEB), Warning: No Input
in 50 msec...
2008-11-02 05:32:32.165 LFireDev(001BDDFFFEF17BEB), Warning: No Input
in 100 msec...
2008-11-02 05:32:32.401 LFireDev(001BDDFFFEF17BEB): Buffered packets
2000 (8000 KB)

How does the backend know which port to look at all of a sudden?  Is
there anyway I can reset the port automatically when it starts looking
at port -1?