How to change poll rate of usb "gamepad" drum controller

I’m trying to increase the USB poll rate of my ION IED05 drum controller to decrease the latency when striking toms. This drum controller is actually behaving like a USB gamepad, instead of being a MIDI instrument. Therefore i’m writing a midi proxy.

Let me first give you some information.

I’m getting events from /dev/input/js0 when striking toms.

I’m running an up-to-date Arch Linux install, with the realtime kernel Linux instrument 5.4.19-rt11-1-rt #1 SMP PREEMPT_RT Fri, 21 Feb 2020 08:55:59 +0000 x86_64 GNU/Linux

On connecting the controller i get the following dmesg output:

[ 3502.121825] usb 2-4.1: new low-speed USB device number 13 using xhci_hcd
[ 3502.238814] usb 2-4.1: New USB device found, idVendor=15e4, idProduct=0100, bcdDevice= 1.00
[ 3502.238817] usb 2-4.1: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[ 3502.238819] usb 2-4.1: Product: DRUM VDX-150
[ 3502.238820] usb 2-4.1: Manufacturer: DRUM VDX-150
[ 3502.257116] input: DRUM VDX-150 DRUM VDX-150 as /devices/pci0000:00/0000:00:14.0/usb2/2-4/2-4.1/2-4.1:1.0/0003:15E4:0100.000D/input/input44
[ 3502.257407] hid-generic 0003:15E4:0100.000D: input,hidraw1: USB HID v1.00 Joystick [DRUM VDX-150 DRUM VDX-150] on usb-0000:00:14.0-4.1/input0

The kernel has this to say about the device:

instrument# cat /sys/kernel/debug/usb/devices | grep DRUM -B3 -A3
T:  Bus=02 Lev=02 Prnt=03 Port=00 Cnt=01 Dev#= 11 Spd=1.5  MxCh= 0
D:  Ver= 1.10 Cls=00(>ifc ) Sub=00 Prot=00 MxPS= 8 #Cfgs=  1
P:  Vendor=15e4 ProdID=0100 Rev= 1.00
S:  Manufacturer=DRUM VDX-150
S:  Product=DRUM VDX-150
C:* #Ifs= 1 Cfg#= 1 Atr=80 MxPwr=100mA
I:* If#= 0 Alt= 0 #EPs= 1 Cls=03(HID  ) Sub=00 Prot=00 Driver=usbhid
E:  Ad=81(I) Atr=03(Int.) MxPS=   8 Ivl=10ms

USB device information:

instrument# lsusb -vd 15e4:0100                     

Bus 002 Device 011: ID 15e4:0100 Numark 
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               1.10
  bDeviceClass            0 
  bDeviceSubClass         0 
  bDeviceProtocol         0 
  bMaxPacketSize0         8
  idVendor           0x15e4 Numark
  idProduct          0x0100 
  bcdDevice            1.00
  iManufacturer           1 DRUM VDX-150
  iProduct                2 DRUM VDX-150
  iSerial                 0 
  bNumConfigurations      1
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength       0x0022
    bNumInterfaces          1
    bConfigurationValue     1
    iConfiguration          0 
    bmAttributes         0x80
      (Bus Powered)
    MaxPower              100mA
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           1
      bInterfaceClass         3 Human Interface Device
      bInterfaceSubClass      0 
      bInterfaceProtocol      0 
      iInterface              0 
        HID Device Descriptor:
          bLength                 9
          bDescriptorType        33
          bcdHID               1.00
          bCountryCode            0 Not supported
          bNumDescriptors         1
          bDescriptorType        34 Report
          wDescriptorLength      86
         Report Descriptors: 
           ** UNAVAILABLE **
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            3
          Transfer Type            Interrupt
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0008  1x 8 bytes
        bInterval              10

At the moment the drumkit is polled every 8ms (i believe 10 is interpreted as 8 by the kernel?), as can be seen from Ivl=10ms

Upon researching if found that i could force the poll rate, i’ve set the usbhid.jspoll parameter like so:

instrument# cat /etc/modprobe.d/usbhid.conf
options usbhid jspoll=1

Which seems to be picked up:

instrument# cat /sys/module/usbhid/parameters/jspoll 
1

But this parameter does not seem to change anything about the poll rate.

I’m testing all this with gilrs, as i’m creating a midi proxy for this drumkit, and the shortest duration i’m seeing between events is 8ms.

I’ve tried everything i could come up with and i don’t know what to try next..

How do i increase the poll rate of this device?