firewire: core: option to log bus reset initiation

Add a debug parameter to firewire-core, analogous to the one in
firewire-ohci. When this is set to 1, log when we schedule, delay, or
initiate a bus reset. Since FireWire bus resets can originate from any
node on the bus, specific logging of the resets we initiate provides
additional insight.
Signed-off-by: Adam Goldman <adamg@pobox.com>
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>

drivers/firewire/core-card.c

@@ -221,11 +221,19 @@ static int reset_bus(struct fw_card *card, bool short_reset)
 	int reg = short_reset ? 5 : 1;
 	int bit = short_reset ? PHY_BUS_SHORT_RESET : PHY_BUS_RESET;
 
+	if (unlikely(fw_core_param_debug & FW_CORE_PARAM_DEBUG_BUSRESETS))
+		fw_notice(card, "initiating %s bus reset\n",
+		          short_reset ? "short" : "long");
+
 	return card->driver->update_phy_reg(card, reg, 0, bit);
 }
 
 void fw_schedule_bus_reset(struct fw_card *card, bool delayed, bool short_reset)
 {
+	if (unlikely(fw_core_param_debug & FW_CORE_PARAM_DEBUG_BUSRESETS))
+		fw_notice(card, "scheduling %s bus reset\n",
+		          short_reset ? "short" : "long");
+
 	/* We don't try hard to sort out requests of long vs. short resets. */
 	card->br_short = short_reset;
 
@@ -244,6 +252,8 @@ static void br_work(struct work_struct *work)
 	/* Delay for 2s after last reset per IEEE 1394 clause 8.2.1. */
 	if (card->reset_jiffies != 0 &&
 	    time_before64(get_jiffies_64(), card->reset_jiffies + 2 * HZ)) {
+		if (unlikely(fw_core_param_debug & FW_CORE_PARAM_DEBUG_BUSRESETS))
+			fw_notice(card, "delaying bus reset\n");
 		if (!queue_delayed_work(fw_workqueue, &card->br_work, 2 * HZ))
 			fw_card_put(card);
 		return;

drivers/firewire/core-transaction.c

@@ -1385,5 +1385,12 @@ static void __exit fw_core_cleanup(void)
 	idr_destroy(&fw_device_idr);
 }
 
+int fw_core_param_debug;
+module_param_named(debug, fw_core_param_debug, int, 0644);
+MODULE_PARM_DESC(debug, "Verbose logging (default = 0"
+	", bus resets = "	__stringify(FW_CORE_PARAM_DEBUG_BUSRESETS)
+	")");
+
+
 module_init(fw_core_init);
 module_exit(fw_core_cleanup);

drivers/firewire/core.h

@@ -238,6 +238,10 @@ static inline bool is_next_generation(int new_generation, int old_generation)
 /* OHCI-1394's default upper bound for physical DMA: 4 GB */
 #define FW_MAX_PHYSICAL_RANGE		(1ULL << 32)
 
+#define FW_CORE_PARAM_DEBUG_BUSRESETS	1
+
+extern int fw_core_param_debug;
+
 void fw_core_handle_request(struct fw_card *card, struct fw_packet *request);
 void fw_core_handle_response(struct fw_card *card, struct fw_packet *packet);
 int fw_get_response_length(struct fw_request *request);