[SOLVED] Zoom R24 in Fedora 42 - no multi-channel I/O

[seablade]

@sciurius

For experimenting I have a KVM/USB switch and I had inserted the R24 USB cable into that switch. And that turned out to be the problem. After plugging the USB cable directly into the PC (or via a decent USB hub) all channels are there!

Ahh yes that will do it. Thanks for letting us know.

Seablade

[ccaudle (Chris)]

@seablade

Ahh yes that will do it.

Will it? Do you think it was because the USB switch forced the connection to a low speed and so the card was forced to use audio class 1 because of the rate limitation?

[sciurius]

I do not know what the switch did to the USB connection. It is USB 2.0, so I would expect it to just switch all 4 wires.
An old page of the switch

These are the log messages in the case of plugging the R24 into the switch:

usb 1-7.4: new full-speed USB device number 39 using xhci_hcd
usb 1-7.4: not running at top speed; connect to a high speed hub
usb 1-7.4: New USB device found, idVendor=1686, idProduct=00dd, bcdDevice= 0.02
usb 1-7.4: New USB device strings: Mfr=1, Product=2, SerialNumber=3
usb 1-7.4: Product: R24
usb 1-7.4: Manufacturer: ZOOM Corporation
usb 1-7.4: SerialNumber: 0
usb 1-7.4: Quirk or no altset; falling back to MIDI 1.0

‘full-speed’ indicates USB 1.1.

When plugged in directly:

usb 1-4.1.4: new high-speed USB device number 52 using xhci_hcd
usb 1-4.1.4: config 1 interface 3 altsetting 0 bulk endpoint 0x1 has invalid maxpacket 64
usb 1-4.1.4: config 1 interface 3 altsetting 0 bulk endpoint 0x82 has invalid maxpacket 64
usb 1-4.1.4: New USB device found, idVendor=1686, idProduct=00dd, bcdDevice= 0.02
usb 1-4.1.4: New USB device strings: Mfr=1, Product=2, SerialNumber=3
usb 1-4.1.4: Product: R24
usb 1-4.1.4: Manufacturer: ZOOM Corporation
usb 1-4.1.4: SerialNumber: 0

Now it is USB 2.0 speed.

[sciurius]

I noticed that the USB hub from the switch itself was registered as a USB 1.1 device. After disconnecting the switch from the PC and reconnecting it registers as a USB 2.0 device.

When I now plug the R24 into the switch, it is also USB 2.0 and everything works.

So apparently for some reason the KVM/USB switch got degraded to USB 1.1.

[seablade]

@ccaudle

Will it? Do you think it was because the USB switch forced the connection to a low speed and so the card was forced to use audio class 1 because of the rate limitation?

So KVMs can be a weird one in my experience. I have seen some for instance that don’t really even pass through USB but rather reimplement the HID to pass through keyboard and mouse commands for instance.

But yes in general any time that a device is only USB1.x compliant (And some KVMs are only 1.x compliant) then you won’t get much beyond the standard 1.0 class compliancy I would venture a guess.

Seablade

[seablade]

@sciurius

I do not know what the switch did to the USB connection. It is USB 2.0, so I would expect it to just switch all 4 wires.

Not necessarily is the thing. In particular you wouldn’t want to have power get disconnected and reconnected for instance for audio interfaces that might be pushing phantom power and running powered monitors, both of those can be a recipe for loud bangs when power cycles. So there is often at least a little more intelligence in how things happen. I don’t know specifics to be able to answer how it is commonly implemented these days, but as I mentioned above, sometimes you get a mixed bag of results from them as a result.

Seablade

[rdtsc]

Hi, just a mention about a peculiarity with USB. Most PCs today don’t completely shut off the USB ports when the PC is off or reset. I’ve personally seen USB devices get “hung up” and refuse to reset properly because of this. Solution is to power off the PC and disconnect it’s power cord. Same with any powered hubs - remove their power source. Sounds stupid, but always try this first, as there’s a good chance it will fix things.