TinyPilot Mt-viki Switch Issues

Hi @bmrb, sorry that you're running into this issue with your KVM.

It sounds like this behavior might be due to how TinyPilot presents itself as a USB device and how your KVM handles keyboard and mouse input.

First, TinyPilot presents itself as a USB hub with a USB keyboard, USB mouse, and USB thumbdrive attached.

Many KVMs (including this Mt-viki) have separate keyboard and mouse ports that expect connections to individual devices. These ports typically don't handle USB devices through a USB hub. However, the data port seems to support USB hubs, since your TinyPilot works (with the exception of hotkey switching). It's likely that hotkey switching only works via the KVM's keyboard USB port - which would explain why hotkeys don't work via the KVM's data port.

I hope that helps! Please let me know if you have any other questions.

Hi David,

I am not sure that's the entire story - if I update the init-usb-gadget script to contain the following then I believe the device is presented as a USB keyboard without the associated hub:

# Adapted from https://github.com/girst/hardpass-sendHID/blob/master/README.md

cd "${USB_GADGET_PATH}"
mkdir -p "${USB_DEVICE_DIR}"
cd "${USB_DEVICE_DIR}"

echo 0x1d6b > idVendor  # Linux Foundation
echo 0x0104 > idProduct # Multifunction Composite Gadget
echo 0x0100 > bcdDevice # v1.0.0
echo 0x0200 > bcdUSB    # USB2

mkdir -p "$USB_STRINGS_DIR"
echo "6b65796d696d6570690" > "${USB_STRINGS_DIR}/serialnumber"
echo "tinypilot" > "${USB_STRINGS_DIR}/manufacturer"
echo "Generic USB Keyboard" > "${USB_STRINGS_DIR}/product"

# Keyboard
mkdir -p "$USB_KEYBOARD_FUNCTIONS_DIR"
echo 1 > "${USB_KEYBOARD_FUNCTIONS_DIR}/protocol" # Keyboard
echo 0 > "${USB_KEYBOARD_FUNCTIONS_DIR}/subclass" # Boot interface subclass
echo 8 > "${USB_KEYBOARD_FUNCTIONS_DIR}/report_length"
# Write the report descriptor
D=$(mktemp)

{
  echo -ne \\x05\\x01       # Usage Page (Generic Desktop Ctrls)
  echo -ne \\x09\\x06       # Usage (Keyboard)
  echo -ne \\xA1\\x01       # Collection (Application)
  echo -ne \\x05\\x08       #   Usage Page (LEDs)
  echo -ne \\x19\\x01       #   Usage Minimum (Num Lock)
  echo -ne \\x29\\x03       #   Usage Maximum (Scroll Lock)
  echo -ne \\x15\\x00       #   Logical Minimum (0)
  echo -ne \\x25\\x01       #   Logical Maximum (1)
  echo -ne \\x75\\x01       #   Report Size (1)
  echo -ne \\x95\\x03       #   Report Count (3)
  echo -ne \\x91\\x02       #   Output (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position,Non-volatile)
  echo -ne \\x09\\x4B       #   Usage (Generic Indicator)
  echo -ne \\x95\\x01       #   Report Count (1)
  echo -ne \\x91\\x02       #   Output (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position,Non-volatile)
  echo -ne \\x95\\x04       #   Report Count (4)
  echo -ne \\x91\\x01       #   Output (Const,Array,Abs,No Wrap,Linear,Preferred State,No Null Position,Non-volatile)
  echo -ne \\x05\\x07       #   Usage Page (Kbrd/Keypad)
  echo -ne \\x19\\xE0       #   Usage Minimum (0xE0)
  echo -ne \\x29\\xE7       #   Usage Maximum (0xE7)
  echo -ne \\x95\\x08       #   Report Count (8)
  echo -ne \\x81\\x02       #   Input (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position)
  echo -ne \\x75\\x08       #   Report Size (8)
  echo -ne \\x95\\x01       #   Report Count (1)
  echo -ne \\x81\\x01       #   Input (Const,Array,Abs,No Wrap,Linear,Preferred State,No Null Position)
  echo -ne \\x19\\x00       #   Usage Minimum (0x00)
  echo -ne \\x29\\x91       #   Usage Maximum (0x91)
  echo -ne \\x26\\xFF\\x00  #   Logical Maximum (255)
  echo -ne \\x95\\x06       #   Report Count (6)
  echo -ne \\x81\\x00       #   Input (Data,Array,Abs,No Wrap,Linear,Preferred State,No Null Position)
  echo -ne \\xC0            # End Collection
} >> "$D"
cp "$D" "${USB_KEYBOARD_FUNCTIONS_DIR}/report_desc"

mkdir -p "${USB_CONFIG_DIR}"
echo 250 > "${USB_CONFIG_DIR}/MaxPower"

CONFIGS_STRINGS_DIR="${USB_CONFIG_DIR}/${USB_STRINGS_DIR}"
mkdir -p "${CONFIGS_STRINGS_DIR}"
echo "Config ${USB_CONFIG_INDEX}: ECM network" > "${CONFIGS_STRINGS_DIR}/configuration"

ln -s "${USB_KEYBOARD_FUNCTIONS_DIR}" "${USB_CONFIG_DIR}/"

usb_gadget_activate

Before:

After:

I can see that the USB device is successfully presented as a single USB keyboard when plugged into the USB Data port, however the same issue persists when plugged into the USB Keyboard port:

Are there any other troubleshooting steps you can recommend?

Cheers,

Ben

Some further testing shows that USB keyboards (like the UHKv2) that contain both a Mouse and Keyboard (which I assume also present as a hub with multiple devices attached) do work when plugged into the Keyboard port of the KVM:

[595372.512650] usb 1-5.2: new full-speed USB device number 108 using xhci_hcd
[595372.734153] usb 1-5.2: New USB device found, idVendor=1d50, idProduct=6124, bcdDevice= 1.02
[595372.735024] usb 1-5.2: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[595372.735878] usb 1-5.2: Product: UHK 60 v2
[595372.736630] usb 1-5.2: Manufacturer: Ultimate Gadget Laboratories
[595372.752464] hid-generic 0003:1D50:6124.000E: hiddev1,hidraw1: USB HID v1.10 Device [Ultimate Gadget Laboratories UHK 60 v2] on usb-0000:00:14.0-5.2/input0
[595372.753617] input: Ultimate Gadget Laboratories UHK 60 v2 as /devices/pci0000:00/0000:00:14.0/usb1/1-5/1-5.2/1-5.2:1.1/0003:1D50:6124.000F/input/input36
[595372.812831] hid-generic 0003:1D50:6124.000F: input,hidraw3: USB HID v1.10 Keyboard [Ultimate Gadget Laboratories UHK 60 v2] on usb-0000:00:14.0-5.2/input1
[595372.814251] input: Ultimate Gadget Laboratories UHK 60 v2 as /devices/pci0000:00/0000:00:14.0/usb1/1-5/1-5.2/1-5.2:1.2/0003:1D50:6124.0010/input/input37
[595372.872781] hid-generic 0003:1D50:6124.0010: input,hidraw4: USB HID v1.10 Device [Ultimate Gadget Laboratories UHK 60 v2] on usb-0000:00:14.0-5.2/input2
[595372.874170] input: Ultimate Gadget Laboratories UHK 60 v2 as /devices/pci0000:00/0000:00:14.0/usb1/1-5/1-5.2/1-5.2:1.3/0003:1D50:6124.0011/input/input38
[595372.932777] hid-generic 0003:1D50:6124.0011: input,hidraw5: USB HID v1.10 Device [Ultimate Gadget Laboratories UHK 60 v2] on usb-0000:00:14.0-5.2/input3
[595372.934389] input: Ultimate Gadget Laboratories UHK 60 v2 as /devices/pci0000:00/0000:00:14.0/usb1/1-5/1-5.2/1-5.2:1.4/0003:1D50:6124.0012/input/input39
[595372.935257] hid-generic 0003:1D50:6124.0012: input,hidraw6: USB HID v1.10 Mouse [Ultimate Gadget Laboratories UHK 60 v2] on usb-0000:00:14.0-5.2/input4
[595372.958495] usbcore: registered new interface driver usbmouse