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Message-ID: <20250918235448.129705-5-o-takashi@sakamocchi.jp>
Date: Fri, 19 Sep 2025 08:54:46 +0900
From: Takashi Sakamoto <o-takashi@...amocchi.jp>
To: linux1394-devel@...ts.sourceforge.net
Cc: linux-kernel@...r.kernel.org
Subject: [PATCH v2 4/6] firewire: core: code refactoring to split contention procedure for bus manager
The precedure to contend for bus manager has much code. It is better to
split it into a helper function.
This commit refactors in the point.
Signed-off-by: Takashi Sakamoto <o-takashi@...amocchi.jp>
---
drivers/firewire/core-card.c | 223 ++++++++++++++++++++---------------
1 file changed, 127 insertions(+), 96 deletions(-)
diff --git a/drivers/firewire/core-card.c b/drivers/firewire/core-card.c
index 02058af705cc..6268b595d4fa 100644
--- a/drivers/firewire/core-card.c
+++ b/drivers/firewire/core-card.c
@@ -279,6 +279,102 @@ void fw_schedule_bm_work(struct fw_card *card, unsigned long delay)
fw_card_put(card);
}
+enum bm_contention_outcome {
+ // The bus management contention window is not expired.
+ BM_CONTENTION_OUTCOME_WITHIN_WINDOW = 0,
+ // The IRM node has link off.
+ BM_CONTENTION_OUTCOME_IRM_HAS_LINK_OFF,
+ // The IRM node complies IEEE 1394:1994 only.
+ BM_CONTENTION_OUTCOME_IRM_COMPLIES_1394_1995_ONLY,
+ // Another bus reset, BM work has been rescheduled.
+ BM_CONTENTION_OUTCOME_AT_NEW_GENERATION,
+ // We have been unable to send the lock request to IRM node due to some local problem.
+ BM_CONTENTION_OUTCOME_LOCAL_PROBLEM_AT_TRANSACTION,
+ // The lock request failed, maybe the IRM isn't really IRM capable after all.
+ BM_CONTENTION_OUTCOME_IRM_IS_NOT_CAPABLE_FOR_IRM,
+ // Somebody else is BM.
+ BM_CONTENTION_OUTCOME_IRM_HOLDS_ANOTHER_NODE_AS_BM,
+ // The local node succeeds after contending for bus manager.
+ BM_CONTENTION_OUTCOME_IRM_HOLDS_LOCAL_NODE_AS_BM,
+};
+
+static enum bm_contention_outcome contend_for_bm(struct fw_card *card)
+{
+ int generation = card->generation;
+ int local_id = card->local_node->node_id;
+ __be32 data[2] = {
+ cpu_to_be32(BUS_MANAGER_ID_NOT_REGISTERED),
+ cpu_to_be32(local_id),
+ };
+ bool grace = time_is_before_jiffies64(card->reset_jiffies + msecs_to_jiffies(125));
+ bool irm_is_1394_1995_only = false;
+ bool keep_this_irm = false;
+ struct fw_node *irm_node;
+ struct fw_device *irm_device;
+ int rcode;
+
+ if (!grace) {
+ if (!is_next_generation(generation, card->bm_generation) || card->bm_abdicate)
+ return BM_CONTENTION_OUTCOME_WITHIN_WINDOW;
+ }
+
+ irm_node = card->irm_node;
+ if (!irm_node->link_on) {
+ fw_notice(card, "IRM has link off, making local node (%02x) root\n", local_id);
+ return BM_CONTENTION_OUTCOME_IRM_HAS_LINK_OFF;
+ }
+
+ irm_device = fw_node_get_device(irm_node);
+ if (irm_device && irm_device->config_rom) {
+ irm_is_1394_1995_only = (irm_device->config_rom[2] & 0x000000f0) == 0;
+
+ // Canon MV5i works unreliably if it is not root node.
+ keep_this_irm = irm_device->config_rom[3] >> 8 == CANON_OUI;
+ }
+
+ if (irm_is_1394_1995_only && !keep_this_irm) {
+ fw_notice(card, "IRM is not 1394a compliant, making local node (%02x) root\n",
+ local_id);
+ return BM_CONTENTION_OUTCOME_IRM_COMPLIES_1394_1995_ONLY;
+ }
+
+ rcode = fw_run_transaction(card, TCODE_LOCK_COMPARE_SWAP, irm_node->node_id, generation,
+ SCODE_100, CSR_REGISTER_BASE + CSR_BUS_MANAGER_ID, data,
+ sizeof(data));
+
+ switch (rcode) {
+ case RCODE_GENERATION:
+ return BM_CONTENTION_OUTCOME_AT_NEW_GENERATION;
+ case RCODE_SEND_ERROR:
+ return BM_CONTENTION_OUTCOME_LOCAL_PROBLEM_AT_TRANSACTION;
+ case RCODE_COMPLETE:
+ {
+ int bm_id = be32_to_cpu(data[0]);
+
+ // Used by cdev layer for "struct fw_cdev_event_bus_reset".
+ scoped_guard(spinlock, &card->lock) {
+ if (bm_id != BUS_MANAGER_ID_NOT_REGISTERED)
+ card->bm_node_id = 0xffc0 & bm_id;
+ else
+ card->bm_node_id = local_id;
+ }
+
+ if (bm_id != BUS_MANAGER_ID_NOT_REGISTERED)
+ return BM_CONTENTION_OUTCOME_IRM_HOLDS_ANOTHER_NODE_AS_BM;
+ else
+ return BM_CONTENTION_OUTCOME_IRM_HOLDS_LOCAL_NODE_AS_BM;
+ }
+ default:
+ if (!keep_this_irm) {
+ fw_notice(card, "BM lock failed (%s), making local node (%02x) root\n",
+ fw_rcode_string(rcode), local_id);
+ return BM_CONTENTION_OUTCOME_IRM_COMPLIES_1394_1995_ONLY;
+ } else {
+ return BM_CONTENTION_OUTCOME_IRM_IS_NOT_CAPABLE_FOR_IRM;
+ }
+ }
+}
+
DEFINE_FREE(node_unref, struct fw_node *, if (_T) fw_node_put(_T))
DEFINE_FREE(card_unref, struct fw_card *, if (_T) fw_card_put(_T))
@@ -305,105 +401,40 @@ static void bm_work(struct work_struct *work)
local_id = card->local_node->node_id;
if (card->bm_generation != generation) {
- bool grace = time_is_before_jiffies64(card->reset_jiffies + msecs_to_jiffies(125));
-
- if (grace ||
- (is_next_generation(generation, card->bm_generation) && !card->bm_abdicate)) {
- // This first step is to figure out who is IRM and
- // then try to become bus manager. If the IRM is not
- // well defined (e.g. does not have an active link
- // layer or does not responds to our lock request, we
- // will have to do a little vigilante bus management.
- // In that case, we do a goto into the gap count logic
- // so that when we do the reset, we still optimize the
- // gap count. That could well save a reset in the
- // next generation.
- __be32 data[2] = {
- cpu_to_be32(BUS_MANAGER_ID_NOT_REGISTERED),
- cpu_to_be32(local_id),
- };
- struct fw_device *irm_device = fw_node_get_device(card->irm_node);
- bool irm_is_1394_1995_only = false;
- bool keep_this_irm = false;
- int rcode;
-
- if (!card->irm_node->link_on) {
- new_root_id = local_id;
- fw_notice(card, "%s, making local node (%02x) root\n",
- "IRM has link off", new_root_id);
- goto pick_me;
- }
+ enum bm_contention_outcome result = contend_for_bm(card);
- if (irm_device && irm_device->config_rom) {
- irm_is_1394_1995_only = (irm_device->config_rom[2] & 0x000000f0) == 0;
-
- // Canon MV5i works unreliably if it is not root node.
- keep_this_irm = irm_device->config_rom[3] >> 8 == CANON_OUI;
- }
-
- if (irm_is_1394_1995_only && !keep_this_irm) {
- new_root_id = local_id;
- fw_notice(card, "%s, making local node (%02x) root\n",
- "IRM is not 1394a compliant", new_root_id);
- goto pick_me;
- }
-
- rcode = fw_run_transaction(card, TCODE_LOCK_COMPARE_SWAP,
- irm_id, generation, SCODE_100,
- CSR_REGISTER_BASE + CSR_BUS_MANAGER_ID,
- data, sizeof(data));
-
- switch (rcode) {
- case RCODE_GENERATION:
- // Another bus reset, BM work has been rescheduled.
- return;
- case RCODE_SEND_ERROR:
- // We have been unable to send the lock request due to
- // some local problem. Let's try again later and hope
- // that the problem has gone away by then.
- fw_schedule_bm_work(card, msecs_to_jiffies(125));
- return;
- case RCODE_COMPLETE:
- {
- int bm_id = be32_to_cpu(data[0]);
-
- // Used by cdev layer for "struct fw_cdev_event_bus_reset".
- scoped_guard(spinlock, &card->lock) {
- if (bm_id != BUS_MANAGER_ID_NOT_REGISTERED)
- card->bm_node_id = 0xffc0 & bm_id;
- else
- card->bm_node_id = local_id;
- }
-
- if (bm_id != BUS_MANAGER_ID_NOT_REGISTERED) {
- // Somebody else is BM. Only act as IRM.
- if (local_id == irm_id)
- allocate_broadcast_channel(card, generation);
- return;
- }
- break;
- }
- default:
- if (!keep_this_irm) {
- // The lock request failed, maybe the IRM
- // isn't really IRM capable after all. Let's
- // do a bus reset and pick the local node as
- // root, and thus, IRM.
- new_root_id = local_id;
- fw_notice(card, "BM lock failed (%s), making local node (%02x) root\n",
- fw_rcode_string(rcode), new_root_id);
- goto pick_me;
- }
- break;
- }
-
- // A node contends for bus manager in this generation.
- card->bm_generation = generation;
- } else {
- // We weren't BM in the last generation, and the last
- // bus reset is less than 125ms ago. Reschedule this job.
+ switch (result) {
+ case BM_CONTENTION_OUTCOME_WITHIN_WINDOW:
fw_schedule_bm_work(card, msecs_to_jiffies(125));
return;
+ case BM_CONTENTION_OUTCOME_IRM_HAS_LINK_OFF:
+ new_root_id = local_id;
+ goto pick_me;
+ case BM_CONTENTION_OUTCOME_IRM_COMPLIES_1394_1995_ONLY:
+ new_root_id = local_id;
+ goto pick_me;
+ case BM_CONTENTION_OUTCOME_AT_NEW_GENERATION:
+ // BM work has been rescheduled.
+ return;
+ case BM_CONTENTION_OUTCOME_LOCAL_PROBLEM_AT_TRANSACTION:
+ // Let's try again later and hope that the local problem has gone away by
+ // then.
+ fw_schedule_bm_work(card, msecs_to_jiffies(125));
+ return;
+ case BM_CONTENTION_OUTCOME_IRM_IS_NOT_CAPABLE_FOR_IRM:
+ // Let's do a bus reset and pick the local node as root, and thus, IRM.
+ new_root_id = local_id;
+ goto pick_me;
+ case BM_CONTENTION_OUTCOME_IRM_HOLDS_ANOTHER_NODE_AS_BM:
+ if (local_id == irm_id) {
+ // Only acts as IRM.
+ allocate_broadcast_channel(card, generation);
+ }
+ fallthrough;
+ case BM_CONTENTION_OUTCOME_IRM_HOLDS_LOCAL_NODE_AS_BM:
+ default:
+ card->bm_generation = generation;
+ break;
}
}
--
2.48.1
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