Merge tag 'firewire-fixes-6.8-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394

a38ff5bb · Linus Torvalds <[email protected]> · 2024-02-10 07:56:39 -08:00

Pull firewire fix from Takashi Sakamoto:
 "A change to accelerate the device detection step in some cases.

  In the self-identification step after bus-reset, all nodes in the same
  bus broadcast selfID packet including the value of gap count. The
  value is related to the cable hops between nodes, and used to
  calculate the subaction gap and the arbitration reset gap.

  When each node has the different value of the gap count, the
  asynchronous communication between them is unreliable, since an
  asynchronous transaction could be interrupted by another asynchronous
  transaction before completion. The gap count inconsistency can be
  resolved by several ways; e.g. the transfer of PHY configuration
  packet and generation of bus-reset.

  The current implementation of firewire stack can correctly detect the
  gap count inconsistency, however the recovery action from the
  inconsistency tends to be delayed after reading configuration ROM of
  root node. This results in the long time to probe devices in some
  combinations of hardware.

  Here the stack is changed to schedule the action as soon as possible"

* tag 'firewire-fixes-6.8-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394:
  firewire: core: send bus reset promptly on gap count error

Commit: a38ff5bbf9799dd944c762412aaebc54818407f5
Parents: 5a7ec870 · 7ed43800

Merge commit. Changes below are compared with the first parent: 5a7ec870.

Changes

1 files changed · +17 −1

File	Status	Add	Del	Content
drivers/firewire/core-card.c	modified	+17	−1	View file

drivers/firewire/core-card.c

View file

diff --git a/drivers/firewire/core-card.c b/drivers/firewire/core-card.c
index 6ac5ff2..8aaa7fc 100644
--- a/drivers/firewire/core-card.c
+++ b/drivers/firewire/core-card.c
@@ -429,7 +429,23 @@ static void bm_work(struct work_struct *work)
 	 */
 	card->bm_generation = generation;
 
-	if (root_device == NULL) {
+	if (card->gap_count == 0) {
+		/*
+		 * If self IDs have inconsistent gap counts, do a
+		 * bus reset ASAP. The config rom read might never
+		 * complete, so don't wait for it. However, still
+		 * send a PHY configuration packet prior to the
+		 * bus reset. The PHY configuration packet might
+		 * fail, but 1394-2008 8.4.5.2 explicitly permits
+		 * it in this case, so it should be safe to try.
+		 */
+		new_root_id = local_id;
+		/*
+		 * We must always send a bus reset if the gap count
+		 * is inconsistent, so bypass the 5-reset limit.
+		 */
+		card->bm_retries = 0;
+	} else if (root_device == NULL) {
 		/*
 		 * Either link_on is false, or we failed to read the
 		 * config rom.  In either case, pick another root.