[ltp] Some experiences with serial ports, internal modem and IR port on TP600E.

[Tom Grydeland]

On Sat, 24 Feb 2001, Thomas Hood wrote:

> > + When booting, or loading the serial modem, the lines appearing in the
> >   log are one of:
> > 
> >     kernel: ttyS00 at 0x03f8 (irq = 4) is a 16550A 
> >     kernel: ttyS02 at 0x03e8 (irq = 4) is a 16550A 
> > 
> >     kernel: ttyS00 at 0x03f8 (irq = 4) is a 16550A 
> >     kernel: ttyS01 at 0x02f8 (irq = 3) is a 16550A 
> 
> Hmm.  Do you have any explanation for this variation?

Yes -- it depends on what settings I've asked for with tpctl and/or
setpnp.

I should probably also mention that when I've tried enabling all the
serial ports using setpnp -b, the reboot process appears to be in two
stages -- the 'pad boots to about where I'd expect to see the LILO:
prompt, then it beeps twice and starts over, next time around the prompt
appears.  I don't know what causes this, but I imagine it has to do with
the BIOS not liking the settings it finds, changing some of them and
rebooting.

> You might want to do
>     setpnp -b 13 on
>     setpnp 13 on
>     setpnp -b 13 irq 4
>     setpnp 13 irq 4
> 
> I don't know how redundant that would be, but it doesn't
> hurt to make sure.
> 
> You can check whether the current configuration was changed
> by using "tpctl --rx".

# tpctl --rsx
resource state:                                       current
   serial port 1:                                     enable  0x3f8 IRQ4
   serial port 2:                                     enable  0x3e8 IRQ4
# setpnp -b 13 off
# tpctl --rs2
resource state:                                       current
   serial port 2:                                     disable 0x3e8 IRQ4
# tpctl --rs2
resource state:                                       current
   serial port 2:                                     disable 0x3e8 IRQ4
# setpnp 13 on
# tpctl --rs2
resource state:                                       current
   serial port 2:                                     disable 0x3e8 IRQ4
# setpnp -b 13 on 
# tpctl --rs2
resource state:                                       current
   serial port 2:                                     disable 0x3e8 IRQ4
# setpnp 13 on
# tpctl --rs2
resource state:                                       current
   serial port 2:                                     disable 0x3e8 IRQ4
# setpnp -b 13 io 0x3e8 irq 4   
# setpnp -b 13 on
# tpctl --rs2
resource state:                                       current
   serial port 2:                                     enable  0x3e8 IRQ4
# setpnp -b 13 off
# tpctl --rs2
resource state:                                       current
   serial port 2:                                     disable 0x3e8 IRQ4
#  

>From the above sequence, it would appear that the way to use 'setpnp' to change the settings being seen by 'tpctl' is this:

# setpnp -b 13 io 0x3e8 irq 4
# setpnp -b 13 on

And to disable the IR port:

# setpnp -b 13 off

> Get two ThinkPads together and run minicom on their
> serial IR ports.  You should be able to send characters
> back and forth between the terminals.  Make sure that the
> baud rates, etc., are the same.

"Get two ThinkPads" -- I wish it were that easy.

I'm afraid the only two IR-enabled devices in my immediate reach are the
Thinkpad and a Palm III.

> There must be an interrupt conflict.  Perhaps the PnP BIOS
> is setting up the IR interface to use IRQ3 when it finds that
> the serial cable interface is using IRQ4; then the  mwavedd.o
> module can't use IRQ3.

Yes, maybe.  Anyway, it's not really a problem.  I just start mwaved
when I need it.

> If you are having problems with serial devices then I would
> recommend trying compiling the kernel with integral serial
> driver.

No thanks -- I have often found that unloading/reloading the serial
module is an excellent way of kickstarting the serial port without
rebooting.

> Thomas

-- 
//Tom Grydeland <Tom.Grydeland@phys.uit.no>


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