Re: How to use an usb interface than is claimed by HID?

From: Jiri Kosina
Date: Sat Jan 20 2007 - 18:57:09 EST


On Sun, 21 Jan 2007, Ivan Ukhov wrote:

> No, it won't do. Imagine that I'm not able to modify the kernel with its
> drivers.

Could I ask you what precisely is the driver you are talking about doing?
Why is it not going to be a part of mainline kernel (i.e. being able to be
put on blacklist easily).

> It should work with usual kernel and HID driver. So I want my driver to
> ask the HID driver to free the interfaces or don't claim them at all. Mb
> there's an example of such a driver?.. obviously there are a lot of HID
> devices and mb a vendor one of them doesn't want to use HID driver for
> one of its interfaces to provide some additional features or something,
> so he should make the kernel use his driver instead of HID...

Sure, there are such in-kernel drivers ... for example Wacom driver. This
driver is in-kernel, and it is hooked inside the usb_hid_configure()
function to be ignored by the HID layer completely, and all the driver
specific handling is handled in drivers/usb/input/wacom*.

(When looking at that code, it looks quite ugly by the way. I have no idea
why wacom driver is not using HID_QUIRK_IGNORE, but has a hardcoded hook
in the usb_hid_configure() instead. I will probably fix this.)

Thanks,

--
Jiri Kosina
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