[PATCH] firewire: core: send bus reset promptly on gap count error

[Adam G. <ad...@po...>]

If we are bus manager and the bus has inconsistent gap counts, send a 
bus reset immediately instead of trying to read the root node's config 
ROM first. Otherwise, we could spend a lot of time trying to read the 
config ROM but never succeeding.

This eliminates a 50+ second delay before the FireWire bus is usable 
after a newly connected device is powered on in certain circumstances.

Signed-off-by: Adam Goldman <ad...@po...>
Link: https://sourceforge.net/p/linux1394/mailman/message/58727806/
---

--- linux-source-6.1.orig/drivers/firewire/core-card.c	2023-09-23 02:11:13.000000000 -0700
+++ linux-source-6.1/drivers/firewire/core-card.c	2024-01-22 04:23:06.000000000 -0800
@@ -435,6 +435,16 @@
 		 * config rom.  In either case, pick another root.
 		 */
 		new_root_id = local_id;
+	} else 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, as permitted by IEEE 1394-2008 8.4.5.2.
+		 */
+		new_root_id = local_id;
+		card->bm_retries = 0;
 	} else if (!root_device_is_running) {
 		/*
		 * If we haven't probed this device yet, bail out now