ieee1394: support for slow links or slow 1394b phy ports

Add support for the following types of hardware:
 + nodes that have a link speed < PHY speed
 + 1394b PHYs that are less than S800 capable
 + 1394b/1394a adapter cable between two 1394b PHYs
Also, S1600 and S3200 are now supported if IEEE1394_SPEED_MAX is raised.

A probing function is added to nodemgr's config ROM fetching routine
which adjusts the allowable speed if an access problem was encountered.
Pros and Cons of the approach:
 + minimum code footprint to support this less widely used hardware
 + nearly no overhead for unaffected hardware
 - ineffective before nodemgr began to read the ROM of affected nodes
 - ineffective if ieee1394 is loaded with disable_nodemgr=1
The speed map CSRs which are published to the bus are not touched by the
patch.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Cc: Hakan Ardo <hakan@debian.org>
Cc: Calculex <linux@calculex.com>
Cc: Robert J. Kosinski <robk@cmcherald.com>
Signed-off-by: Ben Collins <bcollins@ubuntu.com>

drivers/ieee1394/eth1394.c

@@ -502,10 +502,8 @@ static void ether1394_reset_priv (struct net_device *dev, int set_mtu)
 
 	/* Determine speed limit */
 	for (i = 0; i < host->node_count; i++)
-		if (max_speed > host->speed_map[NODEID_TO_NODE(host->node_id) *
-						64 + i])
-			max_speed = host->speed_map[NODEID_TO_NODE(host->node_id) *
-						    64 + i];
+		if (max_speed > host->speed[i])
+			max_speed = host->speed[i];
 	priv->bc_sspd = max_speed;
 
 	/* We'll use our maxpayload as the default mtu */

drivers/ieee1394/hosts.h

@@ -32,7 +32,8 @@ struct hpsb_host {
 
 	int node_count;     /* number of identified nodes on this bus */
 	int selfid_count;   /* total number of SelfIDs received */
-	int nodes_active; /* number of nodes that are actually active */
+	int nodes_active;   /* number of nodes with active link layer */
+	u8 speed[63];       /* speed between each node and local node */
 
 	nodeid_t node_id;   /* node ID of this host */
 	nodeid_t irm_id;    /* ID of this bus' isochronous resource manager */

drivers/ieee1394/ieee1394_core.c

@@ -285,9 +285,9 @@ static int check_selfids(struct hpsb_host *host)
 
 static void build_speed_map(struct hpsb_host *host, int nodecount)
 {
-	u8 speedcap[nodecount];
 	u8 cldcnt[nodecount];
 	u8 *map = host->speed_map;
+	u8 *speedcap = host->speed;
 	struct selfid *sid;
 	struct ext_selfid *esid;
 	int i, j, n;
@@ -354,6 +354,11 @@ static void build_speed_map(struct hpsb_host *host, int nodecount)
 			}
 		}
 	}
+
+	/* assume maximum speed for 1394b PHYs, nodemgr will correct it */
+	for (n = 0; n < nodecount; n++)
+		if (speedcap[n] == 3)
+			speedcap[n] = IEEE1394_SPEED_MAX;
 }
 
 
@@ -554,11 +559,10 @@ int hpsb_send_packet(struct hpsb_packet *packet)
 		return 0;
 	}
 
-	if (packet->type == hpsb_async && packet->node_id != ALL_NODES) {
+	if (packet->type == hpsb_async &&
+	    NODEID_TO_NODE(packet->node_id) != ALL_NODES)
 		packet->speed_code =
-			host->speed_map[NODEID_TO_NODE(host->node_id) * 64
-				       + NODEID_TO_NODE(packet->node_id)];
-	}
+			host->speed[NODEID_TO_NODE(packet->node_id)];
 
 	dump_packet("send packet", packet->header, packet->header_size, packet->speed_code);
 

drivers/ieee1394/nodemgr.c

@@ -38,6 +38,7 @@ struct nodemgr_csr_info {
 	struct hpsb_host *host;
 	nodeid_t nodeid;
 	unsigned int generation;
+	unsigned int speed_unverified:1;
 };
 
 
@@ -57,23 +58,75 @@ static char *nodemgr_find_oui_name(int oui)
 	return NULL;
 }
 
+/*
+ * Correct the speed map entry.  This is necessary
+ *  - for nodes with link speed < phy speed,
+ *  - for 1394b nodes with negotiated phy port speed < IEEE1394_SPEED_MAX.
+ * A possible speed is determined by trial and error, using quadlet reads.
+ */
+static int nodemgr_check_speed(struct nodemgr_csr_info *ci, u64 addr,
+			       quadlet_t *buffer)
+{
+	quadlet_t q;
+	u8 i, *speed, old_speed, good_speed;
+	int ret;
+
+	speed = ci->host->speed + NODEID_TO_NODE(ci->nodeid);
+	old_speed = *speed;
+	good_speed = IEEE1394_SPEED_MAX + 1;
+
+	/* Try every speed from S100 to old_speed.
+	 * If we did it the other way around, a too low speed could be caught
+	 * if the retry succeeded for some other reason, e.g. because the link
+	 * just finished its initialization. */
+	for (i = IEEE1394_SPEED_100; i <= old_speed; i++) {
+		*speed = i;
+		ret = hpsb_read(ci->host, ci->nodeid, ci->generation, addr,
+				&q, sizeof(quadlet_t));
+		if (ret)
+			break;
+		*buffer = q;
+		good_speed = i;
+	}
+	if (good_speed <= IEEE1394_SPEED_MAX) {
+		HPSB_DEBUG("Speed probe of node " NODE_BUS_FMT " yields %s",
+			   NODE_BUS_ARGS(ci->host, ci->nodeid),
+			   hpsb_speedto_str[good_speed]);
+		*speed = good_speed;
+		ci->speed_unverified = 0;
+		return 0;
+	}
+	*speed = old_speed;
+	return ret;
+}
 
 static int nodemgr_bus_read(struct csr1212_csr *csr, u64 addr, u16 length,
                             void *buffer, void *__ci)
 {
 	struct nodemgr_csr_info *ci = (struct nodemgr_csr_info*)__ci;
-	int i, ret = 0;
+	int i, ret;
 
 	for (i = 1; ; i++) {
 		ret = hpsb_read(ci->host, ci->nodeid, ci->generation, addr,
 				buffer, length);
-		if (!ret || i == 3)
+		if (!ret) {
+			ci->speed_unverified = 0;
+			break;
+		}
+		/* Give up after 3rd failure. */
+		if (i == 3)
 			break;
 
+		/* The ieee1394_core guessed the node's speed capability from
+		 * the self ID.  Check whether a lower speed works. */
+		if (ci->speed_unverified && length == sizeof(quadlet_t)) {
+			ret = nodemgr_check_speed(ci, addr, buffer);
+			if (!ret)
+				break;
+		}
 		if (msleep_interruptible(334))
 			return -EINTR;
 	}
-
 	return ret;
 }
 
@@ -1204,6 +1257,8 @@ static void nodemgr_node_scan_one(struct host_info *hi,
 	ci->host = host;
 	ci->nodeid = nodeid;
 	ci->generation = generation;
+	ci->speed_unverified =
+		host->speed[NODEID_TO_NODE(nodeid)] > IEEE1394_SPEED_100;
 
 	/* We need to detect when the ConfigROM's generation has changed,
 	 * so we only update the node's info when it needs to be.  */

drivers/ieee1394/sbp2.c

@@ -1664,10 +1664,8 @@ static int sbp2_max_speed_and_size(struct scsi_id_instance_data *scsi_id)
 
 	SBP2_DEBUG_ENTER();
 
-	/* Initial setting comes from the hosts speed map */
 	scsi_id->speed_code =
-	    hi->host->speed_map[NODEID_TO_NODE(hi->host->node_id) * 64 +
-				NODEID_TO_NODE(scsi_id->ne->nodeid)];
+	    hi->host->speed[NODEID_TO_NODE(scsi_id->ne->nodeid)];
 
 	/* Bump down our speed if the user requested it */
 	if (scsi_id->speed_code > max_speed) {