Re: 1-way modem

bfc@xxxxxxxxxxx (Time Waster) wrote:
Just upgrade from 2.6.9 to 2.6.18 (RHEL4.6 to RHEL 5),

That would suggest that the hardware is functional, and
whatever this is, it's software.

and my dialup
is malfunctioning. I can turn ppp debug on, and see that LCP config
requests are being sent, I can snoop the other side and see that
it's sending the LCP ACK's back, but there's no sign of them back
on the original side.

I also tried a manual test of using minicom to dialing another box, manually
ATAing from minicom, the connect happens, but only when I type on host-A
does it show up on destination host-B. Not the reverse. So it's like
a 1-way port or something. Anyone have any debug ideas for this sort
of problem? Anyone seen it before?

Yep. The incoming data, to be seen, requires that the
UART chip be serviced by the driver/kernel... and that
means an interupt routine gets called when there is
data. That requires two things, usually, one is the IRQ
be correct and the other is the port address be correct.

I suppose there might be something else, but those two are the
clear choices for a culprit...

Looking at a working case, I see that stty -a < /dev/ttyS0 (the modem
port) looks the same, and setserial -a /dev/ttyS0 is basically the same

ttyS0 should be IRQ 4, port 0x03f8.

(I tried setting it to auto_irq with no diff). Looking at
/proc/tty/driver/serial during the PPP negotiation seem to only show
transmissions, not receptions.

I'm past doing the dumber things like trying to run a console at the
same time on the same port.

Thanks for any ideas! (Ideally, someone's hit the same thing and
solved it.)

--
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska) floyd@xxxxxxxxxx
.

Relevant Pages