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>

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>
Clemens Ladisch · Stefan Richter
1 parent c16714704b
Showing 1 changed file with 39 additions and 7 deletions Side-by-side Diff
drivers/firewire/ohci.c
@@ -125,6 +125,7 @@
 	struct fw_ohci *ohci;
 	u32 regs;
 	int total_allocation;
+	bool flushing;
  
 	/*
 	 * List of page-sized buffers for storing DMA descriptors.
@@ -1356,6 +1357,17 @@
 	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 @@
 	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 @@
 		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 @@
 		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 @@
 	/* 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)
...	...	@@ -125,6 +125,7 @@
125	125	struct fw_ohci *ohci;
126	126	u32 regs;
127	127	int total_allocation;
	128	+ bool flushing;
128	129
129	130	/*
130	131	* List of page-sized buffers for storing DMA descriptors.
...	...	@@ -1356,6 +1357,17 @@
1356	1357	return 0;
1357	1358	}
1358	1359
	1360	+static void at_context_flush(struct context *ctx)
	1361	+{
	1362	+ tasklet_disable(&ctx->tasklet);
	1363	+
	1364	+ ctx->flushing = true;
	1365	+ context_tasklet((unsigned long)ctx);
	1366	+ ctx->flushing = false;
	1367	+
	1368	+ tasklet_enable(&ctx->tasklet);
	1369	+}
	1370	+
1359	1371	static int handle_at_packet(struct context *context,
1360	1372	struct descriptor *d,
1361	1373	struct descriptor *last)
...	...	@@ -1365,7 +1377,7 @@
1365	1377	struct fw_ohci *ohci = context->ohci;
1366	1378	int evt;
1367	1379
1368		- if (last->transfer_status == 0)
	1380	+ if (last->transfer_status == 0 && !context->flushing)
1369	1381	/* This descriptor isn't done yet, stop iteration. */
1370	1382	return 0;
1371	1383
...	...	@@ -1399,11 +1411,15 @@
1399	1411	break;
1400	1412
1401	1413	case OHCI1394_evt_missing_ack:
1402		- /*
1403		- * Using a valid (current) generation count, but the
1404		- * node is not on the bus or not sending acks.
1405		- */
1406		- packet->ack = RCODE_NO_ACK;
	1414	+ if (context->flushing)
	1415	+ packet->ack = RCODE_GENERATION;
	1416	+ else {
	1417	+ /*
	1418	+ * Using a valid (current) generation count, but the
	1419	+ * node is not on the bus or not sending acks.
	1420	+ */
	1421	+ packet->ack = RCODE_NO_ACK;
	1422	+ }
1407	1423	break;
1408	1424
1409	1425	case ACK_COMPLETE + 0x10:
...	...	@@ -1416,6 +1432,13 @@
1416	1432	packet->ack = evt - 0x10;
1417	1433	break;
1418	1434
	1435	+ case OHCI1394_evt_no_status:
	1436	+ if (context->flushing) {
	1437	+ packet->ack = RCODE_GENERATION;
	1438	+ break;
	1439	+ }
	1440	+ /* fall through */
	1441	+
1419	1442	default:
1420	1443	packet->ack = RCODE_SEND_ERROR;
1421	1444	break;
1422	1445
...	...	@@ -1721,9 +1744,18 @@
1721	1744	/* FIXME: Document how the locking works. */
1722	1745	spin_lock_irqsave(&ohci->lock, flags);
1723	1746
1724		- ohci->generation = generation;
	1747	+ ohci->generation = -1; /* prevent AT packet queueing */
1725	1748	context_stop(&ohci->at_request_ctx);
1726	1749	context_stop(&ohci->at_response_ctx);
	1750	+
	1751	+ spin_unlock_irqrestore(&ohci->lock, flags);
	1752	+
	1753	+ at_context_flush(&ohci->at_request_ctx);
	1754	+ at_context_flush(&ohci->at_response_ctx);
	1755	+
	1756	+ spin_lock_irqsave(&ohci->lock, flags);
	1757	+
	1758	+ ohci->generation = generation;
1727	1759	reg_write(ohci, OHCI1394_IntEventClear, OHCI1394_busReset);
1728	1760
1729	1761	if (ohci->quirks & QUIRK_RESET_PACKET)