Re: [PATCH] usb: core: Fix bandwidth for devices with invalid wBytesPerInterval

Alan Stern
2026-04-02T02:45:50Z

On Thu, Apr 02, 2026 at 10:14:00AM +0800, Tao Xue wrote:
> As specified in Section 4.14.2 of the xHCI Specification, the xHC
> reserves bandwidth for periodic endpoints according to bInterval and
> wBytesPerInterval (Max ESIT Payload).
>
> Some peripherals report an invalid wBytesPerInterval in their device
> descriptor, which is either 0 or smaller than the actual data length
> transmitted. This issue is observed on ASIX AX88179 series USB 3.0
> Ethernet adapters.

Do we log these invalid values when we parse the endpoint and their
companion descriptors? We should -- and we can fix up any errors then,
just once.

Alan Stern