[patch 17/56] ieee1394: ohci1394: increase AT req. retries, fix ack_busy_X from Panasonic camcorders and others

Greg KH
2009-02-11T00:33:57Z

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2.6.27-stable review patch. If anyone has any objections, please let us know.
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From: Stefan Richter <stefanr@s5r6.in-berlin.de>

Commit 64c634ef83991b390ec0503e61f16efb0ba3c60b 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 .

Tested-by: Mathias Beilstein
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/ieee1394/ohci1394.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/ieee1394/ohci1394.h
+++ b/drivers/ieee1394/ohci1394.h
@@ -26,7 +26,7 @@

#define OHCI1394_DRIVER_NAME "ohci1394"

-#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
#define OHCI1394_MAX_SELF_ID_ERRORS 16