linux/drivers/firewire
Stefan Richter 1038953674 firewire: core: check for 1394a compliant IRM, fix inaccessibility of Sony camcorder
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>
2010-06-02 19:48:13 +02:00
..
core-card.c firewire: core: check for 1394a compliant IRM, fix inaccessibility of Sony camcorder 2010-06-02 19:48:13 +02:00
core-cdev.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394-2.6 2010-05-27 10:22:06 -07:00
core-device.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
core-iso.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394-2.6 2010-04-22 12:54:54 -07:00
core-topology.c
core-transaction.c firewire: core: use separate timeout for each transaction 2010-05-19 00:26:30 +02:00
core.h firewire: core: use separate timeout for each transaction 2010-05-19 00:26:30 +02:00
Kconfig firewire, ieee1394: update Kconfig help 2009-12-29 19:58:17 +01:00
Makefile
net.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
ohci.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394-2.6 2010-05-27 10:22:06 -07:00
ohci.h firewire: ohci: fix up configuration of TI chips 2010-04-10 16:51:14 +02:00
sbp2.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394-2.6 2010-03-03 08:08:44 -08:00