diff options
| author | Stefan Richter <stefanr@s5r6.in-berlin.de> | 2009-01-20 19:10:58 +0100 |
|---|---|---|
| committer | Stefan Richter <stefanr@s5r6.in-berlin.de> | 2009-01-24 11:17:27 +0100 |
| commit | 8b7b6afaa84708d08139daa08538ca3e56c351f1 (patch) | |
| tree | 91b1d27a08f6e28c13f8163cc2dfbba4022029f0 /drivers/ieee1394 | |
| parent | b006854955254a971096c120d4ef115a7c6145fb (diff) | |
| download | linux-8b7b6afaa84708d08139daa08538ca3e56c351f1.tar.gz | |
firewire: ohci: increase AT req. retries, fix ack_busy_X from Panasonic camcorders and others
Camcorders have a tendency to fail read requests to their config ROM and
write request to their FCP command register with ack_busy_X. This has
become a problem with newer kernels and especially Panasonic camcorders,
causing AV/C in dvgrab and kino to fail. Dvgrab for example frequently
logs "send oops"; kino reports loss of AV/C control. I suspect that
lower CPU scheduling latencies in newer kernels made this issue more
prominent now.
According to
https://sourceforge.net/tracker/?func=detail&atid=114103&aid=2492640&group_id=14103
this can be fixed by configuring the FireWire controller for more
hardware retries for request transmission; these retries are evidently
more successful than libavc1394's own retry loop (typically 3 tries on
top of hardware retries).
Presumably the same issue has been reported at
https://bugzilla.redhat.com/show_bug.cgi?id=449252 and
https://bugzilla.redhat.com/show_bug.cgi?id=477279 .
In a quick test with a JVC camcorder (which didn't malfunction like the
reported camcorders), this change decreased the number of ack_busy_X
from 16 in three runs of dvgrab to 4 in three runs of the same capture
duration.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Diffstat (limited to 'drivers/ieee1394')
0 files changed, 0 insertions, 0 deletions