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1038953674
Per IEEE 1394 clause 8.4.2.3, a contender for the IRM role shall check whether the current IRM complies to 1394a-2000 or later. If not force a compliant node (e.g. itself) to become IRM. This was implemented in the older ieee1394 driver but not yet in firewire-core. An older Sony camcorder (Sony DCR-TRV25) which implements 1394-1995 IRM but neither 1394a-2000 IRM nor BM was now found to cause an interoperability bug: - Camcorder becomes root node when plugged in, hence gets IRM role. - firewire-core successfully contends for BM role, proceeds to perform gap count optimization and resets the bus. - Sony camcorder ignores presence of a BM (against the spec, this is a firmware bug), performs its idea of gap count optimization and resets the bus. - Preceding two steps are repeated endlessly, bus never settles, regular I/O is practically impossible. http://thread.gmane.org/gmane.linux.kernel.firewire.user/3913 This is an interoperability regression from the old to the new drivers. Fix it indirectly by adding the 1394a IRM check. The spec suggests three and a half methods to determine 1394a compliance of a remote IRM; we choose the method of testing the Config_ROM.Bus_Info.generation field. This is data that firewire-core should have readily available at this point, i.e. does not require extra I/O. Reported-by: Clemens Ladisch <clemens@ladisch.de> (missing 1394a check) Reported-by: H. S. <hs.samix@gmail.com> (issue with Sony DCR-TRV25) Tested-by: H. S. <hs.samix@gmail.com> Cc: <stable@kernel.org> # .32.x and newer Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de> |
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.. | ||
core-card.c | ||
core-cdev.c | ||
core-device.c | ||
core-iso.c | ||
core-topology.c | ||
core-transaction.c | ||
core.h | ||
Kconfig | ||
Makefile | ||
net.c | ||
ohci.c | ||
ohci.h | ||
sbp2.c |