[lug] Parallel Port Driver/Serial Problem

Lee Woodworth blug-mail at duboulder.com
Mon Mar 31 13:28:56 MDT 2014

On 03/31/2014 01:20 PM, Stephen Queen wrote:
> I wrote a very simple driver that uses the interrupt from the parallel
> port. When I load this driver from either /etc/modules or rc.local, it
> causes the serial port ttyS3 to become intermittent. If I just wait for the
> computer to boot, and do a modprobe of the driver, everything works. Any
> ideas where I could find the problem?
> The serial and parallel port use different addresses and different
> interrupts.

Might be a sequence problem. Is udev autoloading modules? Are there modules
loaded after yours in /etc/modules?

Compare dmesg right after boot for the working and failing cases.

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