linux-kernel - Re: "permanently" unbind a device from a driver?

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Message-ID: <20090120210254.GA5609@kroah.com>
Date:	Tue, 20 Jan 2009 13:02:54 -0800
From:	Greg KH <greg@...ah.com>
To:	Michael Tokarev <mjt@....msk.ru>
Cc:	Linux-kernel <linux-kernel@...r.kernel.org>,
	Linux USB list <linux-usb@...r.kernel.org>
Subject: Re: "permanently" unbind a device from a driver?

On Tue, Jan 20, 2009 at 11:50:07PM +0300, Michael Tokarev wrote:
> Is there a way to stop a module from claiming a
> given device no matter how/when it gets plugged?
> 
> For example, there's a series of power supplies
> (UPSes) with USB connection (common nowadays)
> which, by default, gets claimed by usbhid module.
> But it does not work as a HID device, instead it
> uses a serial line logic and has a USB<=>serial
> converter inside, which works just fine with
> cypress_m8 usbserial driver.
> 
> usbhid module is loaded on startup (to handle
> usb keyboards/mouses), and it claims this device
> too.  Using /sys/bus/.../drivers/usbhid/unbind
> releases it, after which cypress_m8 works as
> expected.  But after re-plugging it gets claimed
> by usbhid again.

Just add a blacklist rule to the usbhid driver for this device.  There
are a number of devices out there that need this functionality, which is
why there is such a list.

> I understand that it's easy to write an udev rule
> (I don't use udev but that's another story) to
> unbind the device from the driver and bind it to
> another driver automatically.  That's basically
> what I have for now (handling hidraw* device).
> But that seems somewhat... ugly, at best.
> 
> The question is: is it possible to tell usbhid
> to STOP claiming devices with given vendor:device
> identifier, from now on?
> 
> I also understand that to do it permanently the
> given vendor:device has to be blacklisted in the
> driver source.  But I don't think it's worth the
> effort.

Why wouldn't it be worth the effort?  It's obviously a problem.

thanks,

greg k-h
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