2.6.28-stable review patch. If anyone has any objections, please let us know. ------------------ From: Stefan Richter <stefanr@s5r6.in-berlin.de> Commit 8b7b6afaa84708d08139daa08538ca3e56c351f1 upstream. 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> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> --- drivers/firewire/fw-ohci.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/firewire/fw-ohci.c +++ b/drivers/firewire/fw-ohci.c @@ -226,7 +226,7 @@ static inline struct fw_ohci *fw_ohci(st #define CONTEXT_DEAD 0x0800 #define CONTEXT_ACTIVE 0x0400 -#define OHCI1394_MAX_AT_REQ_RETRIES 0x2 +#define OHCI1394_MAX_AT_REQ_RETRIES 0xf #define OHCI1394_MAX_AT_RESP_RETRIES 0x2 #define OHCI1394_MAX_PHYS_RESP_RETRIES 0x8 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/