+static
+bool intel_hdcp_is_ksv_valid(u8 *ksv)
+{
+ int i, ones = 0;
+ /* KSV has 20 1's and 20 0's */
+ for (i = 0; i < DRM_HDCP_KSV_LEN; i++)
+ ones += hweight8(ksv[i]);
+ if (ones != 20)
+ return false;
+
+ return true;
+}
+
+static
+int intel_hdcp_read_valid_bksv(struct intel_digital_port *intel_dig_port,
+ const struct intel_hdcp_shim *shim, u8 *bksv)
+{
+ int ret, i, tries = 2;
+
+ /* HDCP spec states that we must retry the bksv if it is invalid */
+ for (i = 0; i < tries; i++) {
+ ret = shim->read_bksv(intel_dig_port, bksv);
+ if (ret)
+ return ret;
+ if (intel_hdcp_is_ksv_valid(bksv))
+ break;
+ }
+ if (i == tries) {
+ DRM_ERROR("Bksv is invalid\n");
+ return -ENODEV;
+ }
+
+ return 0;
+}
+