Hi Greg KH, 1. Old version kernel can support superspeed transfer, the problem was introduced by the following modification: commit eaf6cbe0992052a46d93047dc122fad5126aa3bd Author: Ruslan Bilovol <ruslan.bilovol@xxxxxxxxx> Date: Mon Jul 12 14:55:28 2021 +0200 usb: gadget: f_uac2: add volume and mute support 2. Only ss_ep_int_desc endpoint doesn't have 'SuperSpeed Endpoint Companion Descriptor' followed (All other endpoints have it). So it is a bugfix rather than a feature. Thanks, Jing Leng