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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> |
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| .. | ||
| fw-card.c | ||
| fw-cdev.c | ||
| fw-device.c | ||
| fw-device.h | ||
| fw-iso.c | ||
| fw-ohci.c | ||
| fw-ohci.h | ||
| fw-sbp2.c | ||
| fw-topology.c | ||
| fw-topology.h | ||
| fw-transaction.c | ||
| fw-transaction.h | ||
| Kconfig | ||
| Makefile | ||