[git pull] FireWire fix

From: Stefan Richter
Date: Tue Jun 08 2010 - 08:47:14 EST

Linus, please pull from the for-linus branch at

git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394-2.6.git for-linus

to receive one update which is merely a fix for an old problem from the
POV of the new firewire subsystem, but is a regression fix for those who
migrated from the older ieee1394 to the firewire subsystem.

Stefan Richter (1):
firewire: core: check for 1394a compliant IRM, fix inaccessibility of Sony camcorder

drivers/firewire/core-card.c | 24 +++++++++++++++++++-----
1 files changed, 19 insertions(+), 5 deletions(-)

Long story because it is a post -rc1 pull request:

This update does *not* affect behavior of firewire-core in presence of
professional video devices, professional audio devices, storage devices,
IP-over-1394 capable nodes. It *does* change behavior in presence of
consumer video devices, but in a way that mirrors what the ieee1394 core
driver has always been doing and what I suppose 1394 stacks or other
popular OSs do, a way to which 1394-1995 compliant devices are forwards
compatible and which 1394a-2000 and later specs explicitly require to be

I suspect that there were more and earlier reports of this
interoperability bug of firewire-core with broken firmwares on Sony
camcorders, but I may have easily mistaken them for mere signs of
degraded old hardware on the electrical level instead of an actual
software/firmware problem. Due to feature differences between ieee1394
core and firewire-core we never noticed this firmware bug with the older

commit 10389536742cefbedecb67a5b2906f155cf3a1c3
Author: Stefan Richter <stefanr@xxxxxxxxxxxxxxxxx>
Date: Sun May 30 19:43:52 2010 +0200

firewire: core: check for 1394a compliant IRM, fix inaccessibility of Sony camcorder

Per IEEE 1394 clause, 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.

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@xxxxxxxxxx> (missing 1394a check)
Reported-by: H. S. <hs.samix@xxxxxxxxx> (issue with Sony DCR-TRV25)
Tested-by: H. S. <hs.samix@xxxxxxxxx>

Cc: <stable@xxxxxxxxxx> # .32.x and newer

Signed-off-by: Stefan Richter <stefanr@xxxxxxxxxxxxxxxxx>

diff --git a/drivers/firewire/core-card.c b/drivers/firewire/core-card.c
index 9dcb304..371713f 100644
--- a/drivers/firewire/core-card.c
+++ b/drivers/firewire/core-card.c
@@ -231,7 +231,7 @@ void fw_schedule_bm_work(struct fw_card *card, unsigned long delay)
static void fw_card_bm_work(struct work_struct *work)
struct fw_card *card = container_of(work, struct fw_card, work.work);
- struct fw_device *root_device;
+ struct fw_device *root_device, *irm_device;
struct fw_node *root_node;
unsigned long flags;
int root_id, new_root_id, irm_id, local_id;
@@ -239,6 +239,7 @@ static void fw_card_bm_work(struct work_struct *work)
bool do_reset = false;
bool root_device_is_running;
bool root_device_is_cmc;
+ bool irm_is_1394_1995_only;

spin_lock_irqsave(&card->lock, flags);

@@ -248,12 +249,18 @@ static void fw_card_bm_work(struct work_struct *work)

generation = card->generation;
root_node = card->root_node;
root_device = root_node->data;
root_device_is_running = root_device &&
atomic_read(&root_device->state) == FW_DEVICE_RUNNING;
root_device_is_cmc = root_device && root_device->cmc;
+ irm_device = card->irm_node->data;
+ irm_is_1394_1995_only = irm_device && irm_device->config_rom &&
+ (irm_device->config_rom[2] & 0x000000f0) == 0;
root_id = root_node->node_id;
irm_id = card->irm_node->node_id;
local_id = card->local_node->node_id;
@@ -276,8 +283,15 @@ static void fw_card_bm_work(struct work_struct *work)

if (!card->irm_node->link_on) {
new_root_id = local_id;
- fw_notify("IRM has link off, making local node (%02x) root.\n",
- new_root_id);
+ fw_notify("%s, making local node (%02x) root.\n",
+ "IRM has link off", new_root_id);
+ goto pick_me;
+ }
+ if (irm_is_1394_1995_only) {
+ new_root_id = local_id;
+ fw_notify("%s, making local node (%02x) root.\n",
+ "IRM is not 1394a compliant", new_root_id);
goto pick_me;

@@ -316,8 +330,8 @@ static void fw_card_bm_work(struct work_struct *work)
* root, and thus, IRM.
new_root_id = local_id;
- fw_notify("BM lock failed, making local node (%02x) root.\n",
- new_root_id);
+ fw_notify("%s, making local node (%02x) root.\n",
+ "BM lock failed", new_root_id);
goto pick_me;
} else if (card->bm_generation != generation) {

Stefan Richter
-=====-==-=- -==- -=---

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