+int ehca_calc_ipd(struct ehca_shca *shca, int port,
+ enum ib_rate path_rate, u32 *ipd)
+{
+ int path = ib_rate_to_mult(path_rate);
+ int link, ret;
+ struct ib_port_attr pa;
+
+ if (path_rate == IB_RATE_PORT_CURRENT) {
+ *ipd = 0;
+ return 0;
+ }
+
+ if (unlikely(path < 0)) {
+ ehca_err(&shca->ib_device, "Invalid static rate! path_rate=%x",
+ path_rate);
+ return -EINVAL;
+ }
+
+ ret = ehca_query_port(&shca->ib_device, port, &pa);
+ if (unlikely(ret < 0)) {
+ ehca_err(&shca->ib_device, "Failed to query port ret=%i", ret);
+ return ret;
+ }
+
+ link = ib_width_enum_to_int(pa.active_width) * pa.active_speed;
+
+ if (path >= link)
+ /* no need to throttle if path faster than link */
+ *ipd = 0;
+ else
+ /* IPD = round((link / path) - 1) */
+ *ipd = ((link + (path >> 1)) / path) - 1;
+
+ return 0;
+}
+