[FFADO-user] frequent dropouts and eventual jackserver failure from Xwindow redrawing quirk.

[dmotd <ina...@si...>]

hi folks,

after returned to audio work after some time off i'm experiencing issues
with my edirol fa-101 on a recently updated archlinux laptop. for the
record, i have used ffado on this system in the past with great success
and from memory i believe it  was playing fine with the new firewire
stack, i've also tested against pure:dyne live distro which is a couple
of years old and uses the old stack and there are no problems - which
should rule out hardware failure.

i can start jack with ffado fine and audio is delivered as promised,
ardour will run okay, but i start to get xruns as soon as i do basic
tasks, like altering a windows geometry (any unrelated window) - the
audio completely drops out until i release the mouse. this seems
trivial, but it is far more pronounced when i run pure-data, minor
changes to whats been drawn on the screen (creating objects, moving
things around a patch, changing the contents of an array) create audio
dropouts and make the software almost unusable. this isn't the case
running pure-data with alsa/jack using the internal soundcard. in fact i
discovered this occurs without pure-data running dsp at all, just making
any changes to the patch window effects the running ffado/jack session.
this all occurs regardless of the window manager - i'm currently running
a very stripped back openbox for testing.

the underlying toolkit for pure-data is tcl/tk, and sure enough running
a very basic canvas animation found here: http://wiki.tcl.tk/4293 is
enough to bring ffado to a halt.

i've attached a session where i launch jack while the canvas animation
plays in the background, the jackserver starts but it jams quite quickly
and nothing can connect to it, it has to be forcefully killed (-s 9).

this message is logged in dmesg:
---
firewire_ohci 0000:03:00.0: DMA context IT0 has stopped, error code:
evt_timeout
---

as i type this email (evolution) with ardour running in the background i
get dropouts every time i get to a new line and switching windows
creates dropouts, it's all rather peculiar! not all redrawing actions
seem to effect ffado, just some, i can safely use firefox, draw in gimp
and inkscape with ardour running in the background, but certainly
however tcl/tk implements drawing really nails it.

i'm not really sure how to go about debugging this problem, it must be
very particular to how my system is setup or i suspect this would be
more widely reported? i've attached the output of ffado-diag. hopefully
it helps..

i'm using an svn build (2195) of libffado, but the same thing occurs
with libffado 2.0.1 which is distributed with archlinux.

thanks,
dmotd