USB 3 XHCI limited to 32 USB devices

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mexicanw
Posts: 3
Joined: Sat Feb 29, 2020 8:21 pm

USB 3 XHCI limited to 32 USB devices

Post by mexicanw »

Hi,

I need to connect lots of USB devices to fitlet2. With EHCI (USB 2.0) USB controllers, I was able to connect more than 90 devices but with XHCI only 32 devices are allowed.

Does the fitlet2 have an EHCI controller? Is there an option in the BIOS to switch to USB 2.0 in order to be able to connect more devices?

Thanks

tamir
Site Admin
Posts: 419
Joined: Mon Dec 25, 2017 4:21 pm

Re: USB 3 XHCI limited to 32 USB devices

Post by tamir »

Please provide some examples of devices that you were not allowed?
What's the behavior of a device that doesn't work ?
Please provide machine's S/N and P/N as printed on the white sticker located at the bottom cover.

mexicanw
Posts: 3
Joined: Sat Feb 29, 2020 8:21 pm

Re: USB 3 XHCI limited to 32 USB devices

Post by mexicanw »

Once I connect too much devices, the kernel outputs this message:

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[  272.343677] xhci_hcd 0000:00:15.0: Error while assigning device slot ID                                                                                                 [  272.343699] xhci_hcd 0000:00:15.0: Max number of devices this xHCI host supports is 32.                                                                                 
[  272.343710] usb 1-3-port7: couldn't allocate usb_device                                                   
I connected some USB hubs and barcode scanners (Opticon OPN-2001).

If I try to list all the USB controllers:

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$ lspci -nn |grep -i usb
00:15.0 USB controller [0c03]: Intel Corporation Atom/Celeron/Pentium Processor N4200/N3350/E3900 Series USB xHCI [8086:5aa8] (rev 0b)
The serial number of the fitlet2 is S/N: 1200116-11817.

tamir
Site Admin
Posts: 419
Joined: Mon Dec 25, 2017 4:21 pm

Re: USB 3 XHCI limited to 32 USB devices

Post by tamir »

Our R&D replied that there isn't EHCI controller on the fitlet2, only XHCI that appears to be the bottle neck according to logs provided here on this thread.

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