firewire: core: check for 1394a compliant IRM, fix inaccessibility of Sony camcorder (10389536) · Commits · 戴 / test

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>

drivers/firewire/core-card.c

+19 −5

Original line number	Diff line number	Diff line
		@@ -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;
		fw_node_get(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) {

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