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

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Date:	Thu, 29 Jan 2009 10:43:00 +0100 (CET)
From:	Jiri Kosina <jkosina@...e.cz>
To:	Greg KH <greg@...ah.com>
cc:	Michael Tokarev <mjt@....msk.ru>,
	Sam Liddicott <sam@...dicott.com>,
	Ming Lei <tom.leiming@...il.com>,
	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, 27 Jan 2009, Greg KH wrote:

> > Oh, I didn't know.  In fact, that's exactly what I was asking in my 
> > first email in this thread - to have some module parameter or a sysfs 
> > file which can be touched to stop the module from claiming the device. 
> > This also helps to debug it, to know the right bits to use.. which I 
> > don't know...  ;)
> There is some way to do this, but I can't recall how at the moment.  
> Try asking the HID maintainer about this.

There is a 'quirks=' parameter that can be passed to the usbhid driver. 
Unfortunately the need for IGNORE_QUIRK went away when the whole hid stuff 
got converted to proper bus with proper drivers.

But for backward userspace compatibility we want to have the 
HID_IGNORE_QUIRK in place, solely for the purpose of users being able to 
specify it during the module load, I agree. I currently have this queued 
in my tree.

diff --git a/drivers/hid/usbhid/hid-core.c b/drivers/hid/usbhid/hid-core.c
index f0a0f72..eed05a3 100644
--- a/drivers/hid/usbhid/hid-core.c
+++ b/drivers/hid/usbhid/hid-core.c
@@ -711,6 +711,9 @@ static int usbhid_parse(struct hid_device *hid)
 	quirks = usbhid_lookup_quirk(le16_to_cpu(dev->descriptor.idVendor),
 			le16_to_cpu(dev->descriptor.idProduct));
 
+	if (quirks & HID_QUIRK_IGNORE)
+		return -ENODEV;
+
 	/* Many keyboards and mice don't like to be polled for reports,
 	 * so we will always set the HID_QUIRK_NOGET flag for them. */
 	if (interface->desc.bInterfaceSubClass == USB_INTERFACE_SUBCLASS_BOOT) {
diff --git a/include/linux/hid.h b/include/linux/hid.h
index 81aa84d..da481b3 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -270,6 +270,7 @@ struct hid_item {
 
 #define HID_QUIRK_INVERT			0x00000001
 #define HID_QUIRK_NOTOUCH			0x00000002
+#define HID_QUIRK_IGNORE			0x00000004
 #define HID_QUIRK_NOGET				0x00000008
 #define HID_QUIRK_BADPAD			0x00000020
 #define HID_QUIRK_MULTI_INPUT			0x00000040

-- 
Jiri Kosina
SUSE Labs
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