Hi again,

After some serious investigation problem is solved. And the key of the solution 
is contained by this listgroup.. :-).
As it turned out from this mail 
http://www.mail-archive.com/linux-usb-devel@lists.sourceforge.net/msg13486.html 
, duplicate messages are filtered out in kernel 2.4. I do not understand why it 
works so, and the surrounding kernel code is also strange for me. If I comment 
out that line, it works fine. Keeping the kernel intact, two queries that 
provide different answers work also fine, giving opportunity to hack a horrible 
workaround in the tool.

2.6 kernel code is free from that ominous filtering.

Pete, thank you for your reply,
and you all take care:

Berci

-----Original Message-----
From: Pete Zaitcev [mailto:[EMAIL PROTECTED] 
Sent: Friday, June 22, 2007 12:24 AM
To: Szilvási Bertalan
Cc: linux-usb-devel@lists.sourceforge.net; [EMAIL PROTECTED]
Subject: Re: HID device communication problem with kernel 2.4

On Thu, 21 Jun 2007 22:39:32 +0200, Szilvási Bertalan <[EMAIL PROTECTED]> wrote:

> Communication is done with blocks of 9 values. I send 9 usage_refs to 
> the device using HIDIOCSUSAGE and HIDIOCSREPORT ioctl calls, and wait 
> for the reply. Using cat /dev/usb/hiddev0 I can see that answer has 
> arrived. But only at the first time! After that, no reply arrives, 
> until I press a button on the device. Then the button pressed data can 
> be seen, and after that the serial number query works correctly again 
> for _one_ time, and stops working until the next button event. Setting 
> LEDs and reading button events work always. It seems that only messages that 
> need reply from the device fail.

I see your message, but I don't have an immediate answer. Devices routinely 
communicate blocks of values. This needs looking into. It may be something as 
simple as a missing wake_up(), but I don't know.

Please let me know if you uncover something new and/or come with a patch.

-- Pete

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