ttyS0/1 both on modem port, printer port not working

[Bill Fink]

Hi Jeff,

On Sun Mar 2 2003, Jeff Laughlin wrote:

> I've been trying to figure this out for about 6 hours now, scouring the net 
> for anybody with a similar problem, and I've drawn a complete blank.
> 
> I'm running YDL 2.3 on a PowerMac 7500 604e 180mhz. The modem port works 
> fine. It works fine using ttyS0 AND ttyS1. UNNNHHHH? The printer port 
> doesn't seem connected to any tty's. It doesn't make any sense. The kernel sez:
> PowerMac Z8530 serial driver version 2.0
> ttyS0 at 0xc414a020 (irq = 15) is a Z8530 ESCC, port = modem
> ttyS1 at 0xc4151000 (irq = 16) is a Z8530 ESCC, port = printer
> 
> So again, I connect a serial device to the modem port and I can talk to it 
> on both ttyS0 and ttyS1. I connect a device to the serial device and I 
> can't talk to it on ttyS0 or ttyS1. What is going on here?
> 
> [root@powercrap root]# ls -l /dev/ttyS*
> lr-xr-xr-x    1 root     root            5 Mar  2  2003 /dev/ttyS0 -> tts/0
> lr-xr-xr-x    1 root     root            5 Mar  2  2003 /dev/ttyS1 -> tts/1
> [root@powercrap root]# ls -l /dev/tts*
> total 0
> crw-------    1 root     root       4,  64 Mar  2 02:55 0
> crw-------    1 root     root       4,  65 Jan  1  1970 1

Well it does work on a 7500/100 (which is a 601 processor rather than
your 604e).  One difference is that you're using devfs while I'm not,
although I'm not sure that's significant since the major and minor device
numbers match up.  I'm also using an older 2.4.10-pre8-ben0 kernel.

Since your system is finding the modem and printer ports, it means
you must have MAC_SERIAL configured in your kernel.  Make sure there's
no process running on ttyS1 ("ps tS1") that might be preventing
communication (such as an entry in /etc/inittab with the wrong baud
rate - BTW such a baudrate entry may actually be off by a factor of 2).
Other than that I'm not sure what might be wrong.

						-Bill