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Subject[PATCH 2/2] firewire: cdev: fix fw_cdev_event_bus_reset.bm_node_id
Fix an obscure ABI feature that is a bit of a hassle to implement.
However, somebody put it into the ABI, so let's fill in a sensible
value there.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
---
drivers/firewire/core-card.c | 12 +++++++++---
drivers/firewire/core-cdev.c | 2 +-
drivers/firewire/core-topology.c | 1 +
include/linux/firewire-cdev.h | 5 +++++
include/linux/firewire.h | 1 +
5 files changed, 17 insertions(+), 4 deletions(-)

Index: b/drivers/firewire/core-card.c
===================================================================
--- a/drivers/firewire/core-card.c
+++ b/drivers/firewire/core-card.c
@@ -239,7 +239,7 @@ static void fw_card_bm_work(struct work_
struct fw_card *card = container_of(work, struct fw_card, work.work);
struct fw_device *root_device, *irm_device;
struct fw_node *root_node;
- int root_id, new_root_id, irm_id, local_id;
+ int root_id, new_root_id, irm_id, bm_id, local_id;
int gap_count, generation, grace, rcode;
bool do_reset = false;
bool root_device_is_running;
@@ -315,9 +315,15 @@ static void fw_card_bm_work(struct work_
/* Another bus reset, BM work has been rescheduled. */
goto out;

- if (rcode == RCODE_COMPLETE &&
- card->bm_transaction_data[0] != cpu_to_be32(0x3f)) {
+ bm_id = be32_to_cpu(card->bm_transaction_data[0]);

+ spin_lock_irq(&card->lock);
+ if (rcode == RCODE_COMPLETE && generation == card->generation)
+ card->bm_node_id =
+ bm_id == 0x3f ? local_id : 0xffc0 | bm_id;
+ spin_unlock_irq(&card->lock);
+
+ if (rcode == RCODE_COMPLETE && bm_id != 0x3f) {
/* Somebody else is BM. Only act as IRM. */
if (local_id == irm_id)
allocate_broadcast_channel(card, generation);
Index: b/drivers/firewire/core-cdev.c
===================================================================
--- a/drivers/firewire/core-cdev.c
+++ b/drivers/firewire/core-cdev.c
@@ -319,7 +319,7 @@ static void fill_bus_reset_event(struct
event->generation = client->device->generation;
event->node_id = client->device->node_id;
event->local_node_id = card->local_node->node_id;
- event->bm_node_id = 0; /* FIXME: We don't track the BM. */
+ event->bm_node_id = card->bm_node_id;
event->irm_node_id = card->irm_node->node_id;
event->root_node_id = card->root_node->node_id;

Index: b/drivers/firewire/core-topology.c
===================================================================
--- a/drivers/firewire/core-topology.c
+++ b/drivers/firewire/core-topology.c
@@ -552,6 +552,7 @@ void fw_core_handle_bus_reset(struct fw_
smp_wmb();
card->generation = generation;
card->reset_jiffies = jiffies;
+ card->bm_node_id = 0xffff;
card->bm_abdicate = bm_abdicate;
fw_schedule_bm_work(card, 0);

Index: b/include/linux/firewire-cdev.h
===================================================================
--- a/include/linux/firewire-cdev.h
+++ b/include/linux/firewire-cdev.h
@@ -71,6 +71,10 @@ struct fw_cdev_event_common {
* This event is sent when the bus the device belongs to goes through a bus
* reset. It provides information about the new bus configuration, such as
* new node ID for this device, new root ID, and others.
+ *
+ * If @bm_node_id is 0xffff right after bus reset it can be reread by an
+ * %FW_CDEV_IOC_GET_INFO ioctl after bus manager selection was finished.
+ * Kernels with ABI version < 4 do not set @bm_node_id.
*/
struct fw_cdev_event_bus_reset {
__u64 closure;
@@ -353,6 +357,7 @@ union fw_cdev_event {
* 3 (2.6.34) - made &fw_cdev_get_cycle_timer reliable
* - added %FW_CDEV_IOC_GET_CYCLE_TIMER2
* 4 (2.6.36) - added %FW_CDEV_EVENT_REQUEST2
+ * - implemented &fw_cdev_event_bus_reset.bm_node_id
*/
#define FW_CDEV_VERSION 3 /* Meaningless; don't use this macro. */

Index: b/include/linux/firewire.h
===================================================================
--- a/include/linux/firewire.h
+++ b/include/linux/firewire.h
@@ -119,6 +119,7 @@ struct fw_card {
int bm_retries;
int bm_generation;
__be32 bm_transaction_data[2];
+ int bm_node_id;
bool bm_abdicate;

bool priority_budget_implemented; /* controller feature */
--
Stefan Richter
-=====-==-=- -==- =-=-=
http://arcgraph.de/sr/


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