Isochronous USB Issues » History » Revision 4
Revision 3 (tnt, 01/07/2022 07:52 PM) → Revision 4/24 (tnt, 01/07/2022 08:39 PM)
h1. Isochronous USB Issues
It seems there are many XHCI implementations out there that have problems properly computing the isochronous bandwidth limits and hence refuse to activate both [[icE1usb]] interfaces.
|_.System/Board|_.USB Controller|_.Runs with 2 icE1usb interfaces|
|Raspberry Pi 3B|built-in|YES|
|Raspberry Pi 4|VIA XHCI|no|
|Thinkpad x260|Intel Corporation Sunrise Point-LP USB 3.0 xHCI CoStroller (rev 21)|no|
|PC-Engines APU2|AMD GX-412TC SoC|external:no, internal:YES|
|AMD Ryzen|Ryzen CPU|YES|
|AMD Ryzen|X570 chipset|YES|
|Odroid XU4|USB 2.0 port|YES|
|Odroid XU4|USB 3.0 ports|no|
|Soekris net5501|AMD CS5536 OHCI/EHCI|YES|
Note that in all cases, the device needs to be the sole full speed device on the bus since it uses all the full speed bandwidth and AFAICT all root-hubs are single-TT.
It seems that a hub connected to a EHCI/OHCI port works too, but a hub connected to a XHCI port, even one working without hub, doesn't work. (Currently tested only on Ryzen since it's the only working XHCI controller)