====== EG STARTS USB Joystick Interface ======

{{ eg-starts.jpg?260|EG STARTS Joystick interface}}
The **EG STARTS** is a cheap (10 € in June 2022) circuit to connect a **joystick and buttons** to a PC via the **USB interface**. It is often used to build arcade-style consoles for retrogaming using the MAME software or alike, it is supported by the **GNU/Linux** operating system, but...

===== Problems with GNU/Linux: disconnect loop =====

My first attempt to connect the EG STARTS to a **Raspberry Pi** running the operating system based on **Debian 11 Bullseye** was a total failure. The kernel started an **infinite loop** detecting and disconnecting the USB device:

<code>
usb 2-1.2: new low speed USB device using ehci_hcd and address 7
usb 2-1.2: New USB device found, idVendor=0079, idProduct=0006
usb 2-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=0
usb 2-1.2: Product: Generic   USB  Joystick
usb 2-1.2: Manufacturer: DragonRise inc.
usb 2-1.2: configuration #1 chosen from 1 choice
input: DragonRise inc.   Generic   USB  Joystick   
    as /devices/pci0000:00/0000:00:1a.0/usb2/2-1/2-1.2/2-1.2:1.0/input/input81
dragonrise 0003:0079:0006.004E: input,hidraw2: USB HID v1.10 Joystick
    [DragonRise inc.   Generic   USB  Joystick  ] on usb-0000:00:1a.0-1.2/input0
dragonrise 0003:0079:0006.004E: Force Feedback for DragonRise Inc. game controllers
    by Richard Walmsley <richwalm@gmail.com>
usb 2-1.2: USB disconnect, address 7
</code>

that loop was revealed also by the red **LED** on the interface **blinking** continously.

The problem occurred too using different GNU/Linux distributions: Raspberry Pi OS, Debian GNU/Linux, GRML; all running various **kernel versions** from the **4.x** and **5.x** series. The problem is caused by the kernel driver **hid_dr**, used for **DragonRise Inc. game controller**.

Running an old **2.6** version, the driver (named **hid_drff**) was stable enough to be able to read some input events from the device.

Fortunately I found a workaround for this problem in these posts:

  * **[[https://retropie.org.uk/forum/topic/31488/solved-repeated-disconnect-of-zero-delay-usb-encoder-dragonrise/|Repeated disconnect of Zero Delay USB encoder (DragonRise)]]**
  * **[[https://github.com/sriemer/fix-linux-mouse#usb-mouse-disconnectsreconnects-every-minute-on-linux|USB mouse disconnects/reconnects every minute on Linux]]**

It seems that the problem is caused by the driver that continously does a **buffer overflows if it is not always polled** for events. In that cases the Linux kernel offers a workaround; just add the following option on the **kernel command line**:

<file>
usbhid.quirks=0x0079:0x0006:0x00000400
</file>
In Debian and derived, just add that option into **/etc/default/grub**, at definition of **GRUB_CMDLINE_LINUX**, and execute **update-grub**. Notice that 0x79 is vendor code the and 0x06 is the product code, as revealed by **lsusb**:

<code>
Bus 002 Device 009: ID 0079:0006 DragonRise Inc. Generic USB Joystick
</code>

The bit mask 0x00000400 activates **HID_QUIRK_ALWAYS_POLL**.