Re: uplcom: can only receive data

[Tilman Linneweh <arved%arved.at@localhost>]

* Frederik Sausmikat [ Sep 1, 2008 (15:32 )]:
> ...and I am able to send data *from* a regular built-in serial port  
> *to* the USB adapter but not the other way round (using cat, cu or  
> minicom). This is the case on an Asus EeePC 900 running 4.99.72  
> GENERIC and my home PC running 4.0-STABLE (both i386).
>
> Additionally I tried the adapters with my machine at work, running  
> 4.0-GENERIC (looping tty00 back to ttyU0 via null modem cable) and  
> there they work without any problems (this machine is also i386).
>
> They also work with Debian ("testing", kernel 2.6.26?) on all  
> machines, so it doesn't seem to be hardware related.
>
> Now the question is, does anybody have an idea what the problem  
> might be or any tips on where to start looking in the sources or  
> debugging the problem?

FWIW, i have seen similar behaviour with uplcom devices happening  
sometimes on FreeBSD and MacOS X.
On these systems it usually helps to unplug them and after some time  
replug them in. So i think the hw gets stuck in a strange state.