FC2 hangs when accessing serial device

[Daniel Lawson]

Hi there,

I've just upgraded from FC1 to FC2 on a shuttle PC, 2.4 GHz P4, 
Hauppauge PVR-350. I am using a Sony EVI-D31 PTZ camera with this 
machine. The camera has s-video output into the hauppauge, and a serial 
control channel which you can use to issue movement commands.



This used to work fine in FC1. I needed to upgrade some libraries, so 
upgraded to FC2 at the same time, and now whenever I turn the camera on, 
the machine hangs. Turning the camera off (or unplugging the serial 
cable) causes the machine to resume.


I am using the atrpms version of apt, and all its associated 
repositories as is (clean install of FC2).

It looks like its a probing error, however I've checked everything I can 
think of. No processes seem to execute at all while the machine is hung, 
although the machine still responds to ICMP.

I can reproduce this bug quite easily by plugging the camera in and 
turning it on. The presence of the cable or the cable and the powered 
off camera does not trigger this bug. The camera has to be on for it to 
occur, and the machine will come out of it's hung state immediately upon 
the camera being turned off or the serial cable being disconnected.

I did notice that the LA seemed to hit a high value while the machine 
was locked, although that is probably an artefact of no processes 
executing while it is locked. kacpid does accumulate a lot of system 
time however.

I have checked the following items:

Tested single user mode.
Disabled hotplug (moved /sbin/hotplug out of the way)
Disabled acpi and apm, both using kernel arguments and by recompiling a 
kernel.
Used a vanilla 2.6.7 kernel
Used a vanilla 2.4.26 kernel

I dn't have many other serial devices handy, however I negotiated a null 
modem connection to a different machine using minicom. I have no way of 
testing a full serial connection yet.

None of the above tests helped in any way.

This exact hardware setup worked fine with FC1 previously. The fact that 
a 2.4.26 vanilla kernel showed the same behaviour implies that it is 
probably not a kernel bug, unless the bug manifested itself between 
whichever version of 2.4 I was running previously and 2.4.26. The serial 
system was rewritten in 2.6 I believe.

I'm stumped. I also don't have any more time to work on this, so am 
installing debian unstable on a separate harddisk. I'd prefer to get FC2 
working, as I've invested some time in the previous setup.

Daniel

-- 
Daniel Lawson
WAND Group, Computer Science Department
University of Waikato
email: daniel at wand.net.nz 	phone: +64 7 838 4466  ext 6254