firewire: ohci: flush AT contexts after bus reset for OHCI 1.2

The OHCI 1.2 (draft) specification, clause 7.2.3.3, allows and
recommends that, after a bus reset, the controller does not flush all
the packets in the AT queues.  Therefore, the driver has to do this
itself.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

1 files changed, 39 insertions, 7 deletions

diff --git a/drivers/firewire/ohci.c b/drivers/firewire/ohci.c
index 5e5d5d3d43d1..3372cd187c25 100644
--- a/drivers/firewire/ohci.c
+++ b/drivers/firewire/ohci.c
@@ -125,6 +125,7 @@ struct context {
         struct fw_ohci *ohci;
         u32 regs;
         int total_allocation;
+        bool flushing;
 
         /*
          * List of page-sized buffers for storing DMA descriptors.
@@ -1356,6 +1357,17 @@ static int at_context_queue_packet(struct context *ctx,
         return 0;
 }
 
+static void at_context_flush(struct context *ctx)
+{
+        tasklet_disable(&ctx->tasklet);
+
+        ctx->flushing = true;
+        context_tasklet((unsigned long)ctx);
+        ctx->flushing = false;
+
+        tasklet_enable(&ctx->tasklet);
+}
+
 static int handle_at_packet(struct context *context,
                             struct descriptor *d,
                             struct descriptor *last)
@@ -1365,7 +1377,7 @@ static int handle_at_packet(struct context *context,
         struct fw_ohci *ohci = context->ohci;
         int evt;
 
-        if (last->transfer_status == 0)
+        if (last->transfer_status == 0 && !context->flushing)
                 /* This descriptor isn't done yet, stop iteration. */
                 return 0;
 
@@ -1399,11 +1411,15 @@ static int handle_at_packet(struct context *context,
                 break;
 
         case OHCI1394_evt_missing_ack:
-                /*
-                 * Using a valid (current) generation count, but the
-                 * node is not on the bus or not sending acks.
-                 */
-                packet->ack = RCODE_NO_ACK;
+                if (context->flushing)
+                        packet->ack = RCODE_GENERATION;
+                else {
+                        /*
+                         * Using a valid (current) generation count, but the
+                         * node is not on the bus or not sending acks.
+                         */
+                        packet->ack = RCODE_NO_ACK;
+                }
                 break;
 
         case ACK_COMPLETE + 0x10:
@@ -1416,6 +1432,13 @@ static int handle_at_packet(struct context *context,
                 packet->ack = evt - 0x10;
                 break;
 
+        case OHCI1394_evt_no_status:
+                if (context->flushing) {
+                        packet->ack = RCODE_GENERATION;
+                        break;
+                }
+                /* fall through */
+
         default:
                 packet->ack = RCODE_SEND_ERROR;
                 break;
@@ -1721,9 +1744,18 @@ static void bus_reset_tasklet(unsigned long data)
         /* FIXME: Document how the locking works. */
         spin_lock_irqsave(&ohci->lock, flags);
 
-        ohci->generation = generation;
+        ohci->generation = -1; /* prevent AT packet queueing */
         context_stop(&ohci->at_request_ctx);
         context_stop(&ohci->at_response_ctx);
+
+        spin_unlock_irqrestore(&ohci->lock, flags);
+
+        at_context_flush(&ohci->at_request_ctx);
+        at_context_flush(&ohci->at_response_ctx);
+
+        spin_lock_irqsave(&ohci->lock, flags);
+
+        ohci->generation = generation;
         reg_write(ohci, OHCI1394_IntEventClear, OHCI1394_busReset);
 
         if (ohci->quirks & QUIRK_RESET_PACKET)