+int intel_gmbus_output_aksv(struct i2c_adapter *adapter)
+{
+ struct intel_gmbus *bus = container_of(adapter, struct intel_gmbus,
+ adapter);
+ struct drm_i915_private *dev_priv = bus->dev_priv;
+ int ret;
+ u8 cmd = DRM_HDCP_DDC_AKSV;
+ u8 buf[DRM_HDCP_KSV_LEN] = { 0 };
+ struct i2c_msg msgs[] = {
+ {
+ .addr = DRM_HDCP_DDC_ADDR,
+ .flags = 0,
+ .len = sizeof(cmd),
+ .buf = &cmd,
+ },
+ {
+ .addr = DRM_HDCP_DDC_ADDR,
+ .flags = 0,
+ .len = sizeof(buf),
+ .buf = buf,
+ }
+ };
+
+ intel_display_power_get(dev_priv, POWER_DOMAIN_GMBUS);
+ mutex_lock(&dev_priv->gmbus_mutex);
+
+ /*
+ * In order to output Aksv to the receiver, use an indexed write to
+ * pass the i2c command, and tell GMBUS to use the HW-provided value
+ * instead of sourcing GMBUS3 for the data.
+ */
+ ret = do_gmbus_xfer(adapter, msgs, ARRAY_SIZE(msgs), GMBUS_AKSV_SELECT);
+
+ mutex_unlock(&dev_priv->gmbus_mutex);
+ intel_display_power_put(dev_priv, POWER_DOMAIN_GMBUS);
+
+ return ret;
+}
+