Re: [Libusb-devel] How to dump HID report descriptor under Linux

[Xiaofan C. <xia...@gm...>]

On Sat, Oct 25, 2008 at 12:23 AM, Alan Stern <st...@ro...> wrote:
> On Fri, 24 Oct 2008, Xiaofan Chen wrote:
>> > Is there a simple program to dump the HID report descriptors
>> > under Linux?
>>
>> It turns out lsusb at least partially works. I need to detach the default
>> hiddev kernel driver.
>> http://forum.microchip.com/tm.aspx?m=364987 Post 19.
>>
>> Now the question is how to detach hiddev from interface 1.
>> libhid-detach-device seems to only work for interface 0.
>
> You can detach and attach drivers by hand.  To unbind hiddev from a
> device:
>
>        cd /sys/bus/usb/drivers/hiddev
>        ls
>
> Find the filename for the interface you want to unbind.  Interface
> filenames have the form
>
>        B-P:C.I

I could not find interface filenames there.
mcuee@Ubuntu804:/sys/bus/usb/drivers/hiddev$ ls
bind  module  new_id  uevent  unbind

mcuee@Ubuntu804:/sys/bus/usb/drivers/hiddev$ dmesg
[  620.961917] usb 1-7: new low speed USB device using ohci_hcd and address 7
[  621.176180] usb 1-7: configuration #1 chosen from 1 choice
[  621.186221] input: Chicony USB Keyboard as
/devices/pci0000:00/0000:00:04.0/usb1/1-7/1-7:1.0/input/input4
[  621.227350] input,hidraw2: USB HID v1.11 Keyboard [Chicony USB
Keyboard] on usb-0000:00:04.0-7
[  621.239956] input: Chicony USB Keyboard as
/devices/pci0000:00/0000:00:04.0/usb1/1-7/1-7:1.1/input/input5
[  621.292261] input,hiddev97,hidraw3: USB HID v1.11 Device [Chicony
USB Keyboard] on usb-0000:00:04.0-7

mcuee@Ubuntu804:/sys/bus/usb/drivers/hiddev$ uname -a
Linux Ubuntu804 2.6.24-21-generic #1 SMP Mon Aug 25 17:32:09 UTC 2008
i686 GNU/Linux

> where B is the bus number, P is a string of port numbers separated by
> periods, C is the configuration value, and I is the interface number.
> Having found the filename for the interface you want to unbind, do
>
>        echo -n interface-filename >unbind
>
> To re-attach the driver, do
>
>        echo -n interface-filename >bind
>

While I wrote the above, I found it is actually inside
/sys/bus/usb/drivers/usbhid.

mcuee@Ubuntu804:/sys/bus/usb/drivers/usbhid$ lsusb
Bus 001 Device 007: ID 04f2:0760 Chicony Electronics Co., Ltd
Bus 001 Device 006: ID ffff:0005
Bus 001 Device 005: ID 046d:c054 Logitech, Inc.
Bus 001 Device 004: ID 14c0:0008
Bus 001 Device 003: ID 1947:0033
Bus 001 Device 002: ID 058f:9360 Alcor Micro Corp. 8-in-1 Media Card Reader
Bus 001 Device 001: ID 0000:0000
Bus 002 Device 001: ID 0000:0000

mcuee@Ubuntu804:/sys/bus/usb/drivers/usbhid$ ls
1-3:1.0  1-5:1.0  1-7:1.0  1-7:1.1  bind  module  new_id  uevent  unbind

So far so good. But then there is error thereafter. Maybe this is a Ubuntu
specific problem.

mcuee@Ubuntu804:/sys/bus/usb/drivers/usbhid$ sudo echo -n 1-7:1.0 >unbind
bash: unbind: Permission denied
mcuee@Ubuntu804:/sys/bus/usb/drivers/usbhid$ sudo echo -n 1-7:1.1 >unbind
bash: unbind: Permission denied


Regards,
Xiaofan