[BRLTTY] easy bar on el 40s reacting slowly

[Dave Mielke]

[quoted lines by =?iso-8859-1?Q?J. Sch=F6ber?= on 2007/08/15 at 04:00 +0200]

>I have now installed the very same brltty 3.7.2 from the debian package long 
>with a native and fresh debian on my machine. The problem does not occur any 
>more. 

Good.

>So, I'd bet it's got to do with the virtual machine. 

That's entirely possible. I wish I could be more helpful here, but I've never
tried setting up VMWare, and, even if I were to, it'd be the otehr way around,
i.e.  Windows on top of Linux, so the characteristics would probably be
different anyway.

>Although a friend has it running with no issues at all.

Is he using the very same type of braille display?

>The braille display has only a usb port and is connected via that port. 

Perhaps you need to do something to get the device dedicated to the guest
system. Perhaps VMWare doesn't forward polls by the guest's host controller to
the real bus as frequently as it ought. With USB, the host has to poll the bus
for input, i.e. the device cannot interrupt the host to inform it as soon as it
has made input data available. The device does inform the host how often it
should be polled, so it looks like there may be a problem in this area.

>However the kernel reports a ftdi_sio module being loaded prior to brltty 
>getting active. 

That's probably either udev or hotplug responding to device detection as
Papenmeier uses an FTDI FT232BM chip. That's okay, though, since brltty knows
to steal the device from the kernel driver which has claimed it.

>So I'd think that there is actually a converter in the 
>device itself.

Yes, there is. Papenmeier, like many other braille display manufacturers,
continues to use their well-tested serial interface and puts a USB to serial
adapter in front of it.

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