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>

5 files changed, 76 insertions, 20 deletions

diff --git a/drivers/ieee1394/eth1394.c b/drivers/ieee1394/eth1394.c
index 30fa0d43a43a..b2d2c4dd075b 100644
--- a/drivers/ieee1394/eth1394.c
+++ b/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 */
diff --git a/drivers/ieee1394/hosts.h b/drivers/ieee1394/hosts.h
index 07d188ca8495..d1a47607cb89 100644
--- a/drivers/ieee1394/hosts.h
+++ b/drivers/ieee1394/hosts.h
@@ -30,12 +30,13 @@ struct hpsb_host {
 
         unsigned char iso_listen_count[64];
 
-        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 node_count;     /* number of identified nodes on this bus */
+        int selfid_count;   /* total number of SelfIDs received */
+        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 */
+        nodeid_t node_id;   /* node ID of this host */
+        nodeid_t irm_id;    /* ID of this bus' isochronous resource manager */
         nodeid_t busmgr_id; /* ID of this bus' bus manager */
 
         /* this nodes state */
diff --git a/drivers/ieee1394/ieee1394_core.c b/drivers/ieee1394/ieee1394_core.c
index be6854e25ad4..c83e2b8295e3 100644
--- a/drivers/ieee1394/ieee1394_core.c
+++ b/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);
 
diff --git a/drivers/ieee1394/nodemgr.c b/drivers/ieee1394/nodemgr.c
index 082c7fd239f5..948f1b8c4238 100644
--- a/drivers/ieee1394/nodemgr.c
+++ b/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.  */
diff --git a/drivers/ieee1394/sbp2.c b/drivers/ieee1394/sbp2.c
index 24cd1e250d84..c30e03a0e63b 100644
--- a/drivers/ieee1394/sbp2.c
+++ b/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) {