+/*
+ * 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 error;
+
+ 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;
+ error = hpsb_read(ci->host, ci->nodeid, ci->generation, addr,
+ &q, sizeof(quadlet_t));
+ if (error)
+ 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 error;
+}