known-good serial port doesn't work under FreeBSD

known-good serial port doesn't work under FreeBSD

Post by Richard Rein » Wed, 30 Jul 1997 04:00:00

A small problem, but still of some interest:

I have a FreeBSD 2.2.2 system which contains a standard multi-io card.
Port0 on the card has a 16450 UART, and port1 has a 16550.  The card is
configured for standard IRQs and IO ports.  Both ports are known
(tested today) to be working under DOS, Win95, and even QNX.

There are no ports on the motherboard in the system in question.
There are no conflicting IRQs or IO ports (the only other cards in the
box are the VGa and an NE2000, whose config I have checked carefully).

However, under FreeBSD 2.2.2 *only* port 1 (/dev/ttyd1 and /dev/cuaa1)
works.  Any attempt to access port 0 (/dev/ttyd0 and /dev/cuaa0) stalls
forever -- even 'stty < /dev/ttyd0'.

Any ideas?  Of course, I can just replace the card, but it would be nice
if it worked.


1. Serial port doesn't work!

I have RH5.2 on a Dell Inspiron 3000.  It has a PCMCIA
modem, which cardmgr and setserial seem to indicate is
on /dev/ttyS0, IRQ 3.  The /dev/ttyS* are:

/dev/ttyS0, Line 0, UART: 16550A, Port: 0x03f8, IRQ: 3
/dev/ttyS1, Line 1, UART: unknown, Port: 0x02f8, IRQ: 3
/dev/ttyS2, Line 2, UART: 16550A, Port: 0x03e8, IRQ: 4
/dev/ttyS3, Line 3, UART: unknown, Port: 0x02e8, IRQ: 3

When I probe /dev/ttyS0 while I'm using the modem, it
responds with

/dev/ttyS0: Device or resource busy

After reading the Serial-Programming-HOWTO and the
Serial-HOWTO, I suspect an IRQ conflict, but am not
certain.  I would be much happier if my modem used
IRQ 4 and the serial port were attached to /dev/ttyS1,
because this setup looks kind of strange.  When I
try to listen to incoming data on /dev/ttyS2, nothing
happens.  How can I fix this such that I never have
to worry about it again?

Dave Bailey

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