[BRLTTY] Problem with brltty 3.9 on debian testing

[Dave Mielke]

[quoted lines by Nath on 2008/02/20 at 00:19 +0100]

>I have installed debian testing on my new Asus Eee pc and I encounter a
>problem I never have had before : the braille display turns on sleep
>mode every 4 or 5 seconds. when I press a key on the braille display or
>on the laptop keyboard the braille display is up again but if I don't
>press anything, 4 or 5 seconds after it is in sleep mode again.

You may be a victim of the automatic USB device suspension feature. Brltty 
currently disables this feature for Baum displays, but not for others. Perhaps 
it should arbitrarily disable it for all displays. Let's figure out if this is 
your problem:

Go (cd) to /sys/class/usb_device. In that directory you'll find a bunch of 
devices with names like usbdev1.2. The first digit is the bus number and the 
second digit is the device number.

The next thing to do is to figure out which of those usbdevx.y devices 
corresponds to your display. Each of them is a directory whcih contains, among 
other things, a subdirectory named device. Each of those device subdirectories 
contains, among other things, a file named manufacturer. So, for example, to 
check usbdev1.2, see what usbdev1.2/device/manufacturer says. Find the one 
which names the manufacturer of your display.

When you find the usbdevx.y device which corresponds to your display, cd to 
usbdevx.y/device/power. In there you'll find a file called autosuspend. Write 
-1 to it, like this (assuming usbdev1.2):

   cd usbdev1.2/device/power
   echo >autosuspend -1

Please let us know if this resolves your problem. If so, brltty will be updated 
to handle this problem automatically.

One important thing to note is that the usbdevx.y name will change each time 
you disconnect and reconnect your display so don't do that after you've written 
to its autosuspend file else you'll have to do it again.

-- 
Dave Mielke           | 2213 Fox Crescent | I believe that the Bible is the
Phone: 1-613-726-0014 | Ottawa, Ontario   | Word of God. Please contact me
EMail: dave at mielke.cc | Canada  K2A 1H7   | if you're concerned about Hell.
http://FamilyRadio.com/                   | http://Mielke.cc/bible/