is there a reason "usbhid.quirks" parameter is not root writable?

[Bjørn Mork]

"Robert P. J. Day" <rpjday at crashcourse.ca> writes:
> On Thu, 12 Nov 2015, Greg KH wrote:
>
>> You can add a runtime quirk to the device itself when it shows up in
>> sysfs for the hid driver.  Use that instead of the module parameter for
>> that specific device.
>
>   sorry, i'm not sure what you're suggesting here.

I don't know if this was what Greg meant, but you can always use

 /sys/bus/usb/drivers/usbhid/unbind

to unbind the device from the usbhid driver.  Then you can manually bind
it to some other driver supporting the same device using the same
mechanism (with s/un// of course), or load another supporting driver to
make it probe and bind the device.

Hmm, I was going to point you to the file documenting bind/unbind for
the usb bus, but it doesn't seem to exist?  There you have a task for
someone wanting to improve the docs :)

Anyway, it goes like this: Look at the device driver binding in sysfs:

$ ls -l /sys/bus/usb/drivers/usbhid
total 0
lrwxrwxrwx 1 root root    0 Nov 13 09:06 4-4:1.0 -> ../../../../devices/pci0000:00/0000:00:1d.7/usb4/4-4/4-4:1.0
--w------- 1 root root 4096 Nov 13 09:06 bind
lrwxrwxrwx 1 root root    0 Nov 13 09:06 module -> ../../../../module/usbhid
-rw-r--r-- 1 root root 4096 Nov 13 09:06 new_id
-rw-r--r-- 1 root root 4096 Nov 13 09:06 remove_id
--w------- 1 root root 4096 Nov 13 09:06 uevent
--w------- 1 root root 4096 Nov 13 09:06 unbind


Unbind the device you want to move somewhere else:

$ echo 4-4:1.0 >/sys/bus/usb/drivers/usbhid/unbind

Bind it to 'otherdriver':

$ echo 4-4:1.0 >/sys/bus/usb/drivers/'otherdriver'/bind

(wich will only succeed of that driver's probe succeeds, of course.  If
you need to add a device ID to another driver, then do that using
'new_id' instead.  Which will trigger automatic probing of 'free'
devices)



Bjørn