proposed fix to usb-core

proposed fix to usb-core

[Martin F Krafft]

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We are currently fighting with a problem with the USB HID API, which
seems to prevent a user space application to write more than 32 bit
into a HID field.

We think that this problem can be solved with one of two little
changes to /drivers/usb/hid-core.c (2.4.22 tree):

Function hid_register_field at usb-core.c:96:
  static struct hid_field *hid_register_field(struct hid_report *report, unsigned usages, unsigned values)

The function either needs to duplicate the struct hid_usage or grow
the size of the last struct hid_usage. The first option is the
easiest since it does not require a change of hiddev API. The later
option is probably more effective but requires to change the
HIDIOCSUSAGE ioctl so that it accepts a struct {void* data, int
data_size} instead of just int data. 

I would be happy to submit a patch, but would like to hear first
which option is favourable. The first costs performance and memory,
the second an API change.

Or is there a specific reason why only 32 bits are writeable?

Thanks,

-- 
Martin F. Krafft                Artificial Intelligence Laboratory
Ph.D. Student                   Department of Information Technology
Email: krafft@ailab.ch          University of Zurich
Tel: +41.(0)1.63-54323          Andreasstrasse 15, Office 2.20
http://ailab.ch/people/krafft   CH-8050 Zurich, Switzerland
 
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Re: proposed fix to usb-core

[Loic Dachary]

	Hi,

	For information this problem is already know to Vojtech Pavlik
<vojtech@suse.cz> and was reported last month on linux-usb-devl
(http://marc.theaimsgroup.com/?l=linux-usb-devel&m=106708259416772&w=2).

	Cheers,

-- 
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Loic Dachary, 12 bd Magenta, 75010 Paris. Tel: 33 1 42 45 07 97      
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