1 files changed, 28 insertions, 7 deletions

diff --git a/sound/firewire/fcp.c b/sound/firewire/fcp.c
index 860c08073c59..6876bfa9f27d 100644
--- a/sound/firewire/fcp.c
+++ b/sound/firewire/fcp.c
@@ -30,6 +30,7 @@ enum fcp_state {
         STATE_PENDING,
         STATE_BUS_RESET,
         STATE_COMPLETE,
+        STATE_DEFERRED,
 };
 
 struct fcp_transaction {
@@ -40,6 +41,7 @@ struct fcp_transaction {
         unsigned int response_match_bytes;
         enum fcp_state state;
         wait_queue_head_t wait;
+        bool deferrable;
 };
 
 /**
@@ -81,6 +83,9 @@ int fcp_avc_transaction(struct fw_unit *unit,
         t.state = STATE_PENDING;
         init_waitqueue_head(&t.wait);
 
+        if (*(const u8 *)command == 0x00 || *(const u8 *)command == 0x03)
+                t.deferrable = true;
+
         spin_lock_irq(&transactions_lock);
         list_add_tail(&t.list, &transactions);
         spin_unlock_irq(&transactions_lock);
@@ -93,11 +98,21 @@ int fcp_avc_transaction(struct fw_unit *unit,
                                          (void *)command, command_size, 0);
                 if (ret < 0)
                         break;
-
+deferred:
                 wait_event_timeout(t.wait, t.state != STATE_PENDING,
                                    msecs_to_jiffies(FCP_TIMEOUT_MS));
 
-                if (t.state == STATE_COMPLETE) {
+                if (t.state == STATE_DEFERRED) {
+                        /*
+                         * 'AV/C General Specification' define no time limit
+                         * on command completion once an INTERIM response has
+                         * been sent. but we promise to finish this function
+                         * for a caller. Here we use FCP_TIMEOUT_MS for next
+                         * interval. This is not in the specification.
+                         */
+                        t.state = STATE_PENDING;
+                        goto deferred;
+                } else if (t.state == STATE_COMPLETE) {
                         ret = t.response_size;
                         break;
                 } else if (t.state == STATE_BUS_RESET) {
@@ -132,7 +147,8 @@ void fcp_bus_reset(struct fw_unit *unit)
         spin_lock_irq(&transactions_lock);
         list_for_each_entry(t, &transactions, list) {
                 if (t->unit == unit &&
-                    t->state == STATE_PENDING) {
+                    (t->state == STATE_PENDING ||
+                     t->state == STATE_DEFERRED)) {
                         t->state = STATE_BUS_RESET;
                         wake_up(&t->wait);
                 }
@@ -186,10 +202,15 @@ static void fcp_response(struct fw_card *card, struct fw_request *request,
 
                 if (t->state == STATE_PENDING &&
                     is_matching_response(t, data, length)) {
-                        t->state = STATE_COMPLETE;
-                        t->response_size = min((unsigned int)length,
-                                               t->response_size);
-                        memcpy(t->response_buffer, data, t->response_size);
+                        if (t->deferrable && *(const u8 *)data == 0x0f) {
+                                t->state = STATE_DEFERRED;
+                        } else {
+                                t->state = STATE_COMPLETE;
+                                t->response_size = min_t(unsigned int, length,
+                                                         t->response_size);
+                                memcpy(t->response_buffer, data,
+                                       t->response_size);
+                        }
                         wake_up(&t->wait);
                 }
         }