Editing Quirks for a USB driver

Question

I have a device which is using the usbhid driver.

I noticed a module folder inside the driver with a file name quirks.Can anyone tell me the correct way to edit this file and the values it can take?

    root@raspberrypi:/sys/bus/hid/drivers/generic-usb/module/parameters# dir
    ignoreled  mousepoll  quirks

By default it only contains the following value.

    (null),(null),(null),(null)

Answer 1

I believe you can find a list by module with modinfo

$ modinfo usbhid
...
parm:           quirks:Add/modify USB HID quirks by specifying  quirks=vendorID:productID:quirks where vendorID, productID, and quirks are all in 0x-prefixed hex (array of charp)

And you can give them as parameters while loading a module.

$ sudo modprobe -v usbhid "quirks=0xDEAD:0xBEEF:0x55AA"

I believe you can also just write these into a sysfs file at runtime in some cases. Seems the usbhid is read-only on my (desktop) system, though.

$ echo "0xDEAD:0xBEEF:0x55AA" | sudo tee -a /sys/module/usbhid/parameters/quirks
tee: /sys/module/usbhid/parameters/quirks: Permission denied

I haven't looked into these more and you'll need to find the actual values from somewhere (source, LXR?), but maybe that's a start.

Answer 2

A real world example that I use

cat /sys/module/usb_storage/parameters/quirks
0bc2:3312:u,0bc2:ab38:u

Note that the format is vendor:device:flag[,...] and that , not \n must be used for multiple devices. There is a list of valid flags in the source here.