jackd 0.116.1 with ffado 1.999.43 on Ubuntu Karmic:
libffado1 2.0~rc2+svn1569-2ubuntu1
jackd 0.116.1-4ubuntu2
Sound card: Edirol FA-66
FireWire? card: Texas Instruments TSB82AA2 IEEE-1394b Link Layer Controller (rev 01)
I start jackd with:
jackd -R -d firewire -r 44100 -n 4 -p 2048 -v3
After a minute or so I get a constant flow of error messages like these:
13010291434: Error (CycleTimerHelper?.cpp)[ 508] Execute: negative step: -6311384749.779715! (correcting to nominal)
13010491434: Error (CycleTimerHelper?.cpp)[ 508] Execute: negative step: -6383674302.787433! (correcting to nominal)
13010691448: Error (CycleTimerHelper?.cpp)[ 508] Execute: negative step: -6457904604.647587! (correcting to nominal)
13010891442: Error (CycleTimerHelper?.cpp)[ 508] Execute: negative step: -6534075049.204482! (correcting to nominal)
13011091439: Error (CycleTimerHelper?.cpp)[ 508] Execute: negative step: -6612185921.561870! (correcting to nominal)
They appear about 5-10 times a second. Functionality doesn't seem to be affected though - sound plays just fine. I do get some XRUNs now and then though, but I'm not sure they're related to these errors.
I'm attaching the full output log of the above command.