On Thu, 17 Jun 2004, Helmar Spangenberg wrote:

> Hello,
> 
> the Fujitsu/Siemens Celsius Mobile H Laptop has a removable keyboard with a 
> mousepad which operates on a bluetooth link, which in turn ends up in the usb 
> driver.
> 
> Unfortunately, the original usb configuration (I'm using kernel 2.6.4 with the 
> SuSE patches) does NOT work with the keyboard (probably the protocol is 
> somewhat faulty...). However, I was able to find a workaround to this 
> problem:
> I disabled the functions uhci_inc_fsbr and uhci_dec_fsbr (both in uhci-hcd.c) 
> by adding a "return" statement as first instruction. Well, after 
> initialization of the usb stuff, the keyboard has to be reset (switch off and 
> on), but afterwards it is usable without any problems.
> 
> Since I don't have too much knowledge about usb, is there anybody out there to 
> explain to me, what I am doing with this manipulation?
> 
> Is it possible to add a switch (or some automagic) to eliminate the need of 
> this workaround? In case it's needed, I will be glad to test any new code on 
> the Celsius.
> 
> Thanks,
> Helmar

This sounds like exactly the same problem Alexander Kulakov had.  Read 
the thread starting with

http://marc.theaimsgroup.com/?l=linux-usb-devel&m=108551452932053&w=2

The eventual workaround we found is in the second-to-last message of the
thread.  It's not a good solution because it will reduce performance for
everybody, not just people with broken USB-Bluetooth interfaces.

In simple terms, that patch reduces the rate at which USB packets are sent 
to the Bluetooth controller to about 1 per millisecond.  Apparently it 
can't handle a higher data rate.

Alan Stern



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