[mythtv-users] Firewire (P2P) connection to Motorola DCH-3200 periodically dies after upgrading from 0.23 to 0.25/0.26

[Kevin Worth]

> Not only did you upgrade MythTV, you upgraded your OS, and more
> specifically, your firewire drivers.  It may be the case you have moved
> from the older "ieee1394" stack to the newer"juju" stack, or in any
> case, likely got the latest versions of the firewire drivers.

That's a good point and something I should have thought about. I
didn't realize the 1394 stack had been changed, but over two years,
that's not surprising.

> If you have not done so, be sure you have followed the advice found
> on the wiki at http://www.mythtv.org/wiki/FireWire

With the change in Firewire stacks in mind, I read this page more
carefully, specifically:

http://www.mythtv.org/wiki/FireWire#Plugctl
"For the most reliable FireWire operation, use Point2Point/p2p. By
default your n_p2p_connections will be set to '0'. This mode presented
unreliable operation with dct6200's for recording and watching. Set
p2p to 1."

That's when I noticed...

$ plugreport
Host Adapter 0
==============

Node 0 GUID 0x002374fffe366ce7
------------------------------
oMPR n_plugs=1, data_rate=2, bcast_channel=63
oPCR[0] online=1, bcast_connection=0, n_p2p_connections=0
        channel=0, data_rate=2, overhead_id=0, payload=376
iMPR n_plugs=0, data_rate=2


Uh oh...


$ firewire_tester -p -n0 -r5
Action: Test P2P connection 5 times, node 0, channel 0
P2P: Testing...Success, 356 packets received
P2P: Testing...Success, 365 packets received
P2P: Testing...libiec61883 warning: Failed to allocate bandwidth.
Failed
P2P: Testing...libiec61883 warning: Failed to allocate bandwidth.
Failed
P2P: Testing...libiec61883 warning: Failed to allocate bandwidth.
Failed


Yeah I'd call that unreliable...


$ plugctl -n0 "oPCR[0].n_p2p_connections=1"

$ firewire_tester -p -n0 -r5
Action: Test P2P connection 5 times, node 0, channel 0
P2P: Testing...Success, 399 packets received
P2P: Testing...Success, 360 packets received
P2P: Testing...Success, 234 packets received
P2P: Testing...Success, 345 packets received
P2P: Testing...Success, 319 packets received

Seems quite a bit better...

Added to my /etc/init/mythtv-backend.conf after "pre-start script":
    [ -x /usr/bin/plugctl ] || exit 0
    /usr/bin/plugctl -n 0 "oPCR[0].n_p2p_connections=1"

Rebooted and will now see if things go off into the weeds again.
Thanks for the suggestions!