ieee1394: support for slow links or slow 1394b phy ports
[linux-3.10.git] / drivers / ieee1394 / nodemgr.c
index 082c7fd..948f1b8 100644 (file)
@@ -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.  */