[BRLTTY] Braille displays lags after a kernel upgrade

[Lars Bjørndal]

Dave Mielke <dave at mielke.cc> writes:

> [quoted lines by Lars Bjørndal on 2010/04/05 at 21:53 +0200]
>
>>After a kernel upgrade, maybe from 2.6.31 to 2.6.32, my braille display,
>>a Handy Tech Braille Star 40 on bluetooth, lags a bit. If I press a key
>>on the display to scroll, it takes half a second before it reacts. I
>>feel it's tied to some sleeping issues, because it doesn't happen
>>always. I upgraded to yesterdays svn version of BRLTTY, and the same
>>problem percists.
>>
>>I'm running Fedora 12 on a Lenovo Thinkpad X61S (32bit version). What
>>could I do to solve this problem?
>
> It may be coincidental, but I've noticed posts on the USB developers list which 
> have the phrase "btusb autosuspend" in their subjects. I assume that btusb 
> refers to Bluetooth USB donglesi, or, at least, some flavour of using Bluetooth 
> via USB. Perhaps, therefore, you could try telling your system not to 
> autosuspend your Bluetooth USB device (assuming that's what you have).
Thank you! I worked around the problem by putting the following into my
/etc/rc.local file:

cd `readlink -f /sys/class/bluetooth/hci0`
cd ../../../power
echo 20 > autosuspend

Lars