linux-kernel - Re: hid device not claimed but /dev/input/event exists

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Message-ID: <47BB1515.1070608@dbservice.com>
Date:	Tue, 19 Feb 2008 18:42:45 +0100
From:	Tomas Carnecky <tom@...ervice.com>
To:	Jiri Kosina <jkosina@...e.cz>
CC:	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: hid device not claimed but /dev/input/event exists

Jiri Kosina wrote:
> On Tue, 19 Feb 2008, Tomas Carnecky wrote:
> 
>> usb 1-2.2: new full speed USB device using ehci_hcd and address 6
>> usb 1-2.2: configuration #1 chosen from 1 choice
>> HID device claimed by neither input, hiddev nor hidraw
>> input: Logitech Z-10 USB Speaker as
>> /devices/pci0000:00/0000:00:02.1/usb1/1-2/1-2.2/1-2.2:1.3/input/input4
>> input: USB HID v1.10 Device [Logitech Z-10 USB Speaker] on
>> usb-0000:00:02.1-2.2
>> Nobody claims the device and yet an evdev device shows up in /dev/input? That
> 
> Yes, that looks indeed bogus.
> 
>> I enabled HID_DEBUG, but no debug messages show up in my dmesg output, 
>> which is strange. 
> 
> You have to modprobe the 'hid' module with 'debug=1' parameter. Please 
> send me the resulting output.
> 

Attached is the dump from dmesg.

The device apparently has four 'interfaces' - whatever that is, see [1].
It seems like usbhid probes interface 2 (which is the LCD plus a few
buttons, probably the four just under the LCD, as described [1]).
Because usbhid doesn't know how to handle the buttons, it fails. But
then it probes interface 3 which is a 'proper' HID device with
well-defined buttons.

But still nothing shows up if I press the buttons. But something is
strange, neither does when I press buttons on my sidewinder pad. Unless
I 'cat /dev/input/event5' and then press the buttons, then they shows up
in dmesg. But that trick doesn't work with the Z-10 speakers. Maybe the 
alsa driver is interfering somehow?

[1]
http://forums.logitech.com/logitech/board/message?board.id=stereo_20&message.id=633#M633

View attachment "dump" of type "text/plain" (20930 bytes)