Serial Ports

Serial Ports

[Stephen Torri]

Should serial ports be assigned interrupts on start up or are they
assigned when they are used? I have been tracking the serial ports on my
Supermicro Dual P3 Board for a few days now. At times I cannot get them to
work so I can syncronize a Palm Pilot via the serial port.

Stephen

Re: Serial Ports

[Stuart MacDonald]

From: "Stephen Torri" <storri@ameritech.net>
> Should serial ports be assigned interrupts on start up or are they
> assigned when they are used? I have been tracking the serial ports on my
> Supermicro Dual P3 Board for a few days now. At times I cannot get them to
> work so I can syncronize a Palm Pilot via the serial port.

On-board serial ports are given either the standard irqs, or the
irqs that you specify in the bios. ISA and other non-self-identifying-
bus-based ports will be given the irqs you specify in the configuration
of the device. PCI and other self-identifying-bus-based ports will
be assigned free or sharable irqs by the bios/os. All serial hardware
is assigned an irq. This is the hardware level.

I think what you're asking is "When I cat /proc/irq, should I see the
serial ports listed at boot, or only after I've used them?" The answer
to that is that the standard serial driver only registers to use the
irq that has been assigned, when it needs to use it. So if you check
before usage, you won't see your ports.

..Stu

Re: Serial Ports

[Stephen Torri]

On Wed, 5 Sep 2001, D. Stimits wrote:

> Make sure your bios is set to "not plug-n-play aware". I have a
> Supermicro Dual P3 board that works fine (actually, 2) with serial mice.
> In the case of the modem serial port, I have to use setserial to get the
> characteristics I want, plus the setserial options seem to require
> speed_normal and skip_test to work correctly. Incidentally, if your
> board is based on the i840 chipset, you'll have to run noapic or it will
> die under some circumstances, such as heavy disk load, or rapid
> mount/umount of any filesystem (even a cdrom).
>
> D. Stimits, stimits@idcomm.com

I have noticed that serial ports change IRQ to either 3 or 4. There is no
reason for this behavior. I have created a perl script to create a log
containing the irqs assigned and their ioports. Is there anything else I
could log that might unmask the problem?

So far if the serials are assigned to IRQ 4 then the sync with the palm
pilot doesn't work (/dev/pilot = /dev/ttyS0). If its IRQ 3 then it does.

Stephen

Re: Serial Ports

[Stuart MacDonald]

From: "Stephen Torri" <storri@ameritech.net>
> I have noticed that serial ports change IRQ to either 3 or 4. There is no
> reason for this behavior. I have created a perl script to create a log
> containing the irqs assigned and their ioports. Is there anything else I
> could log that might unmask the problem?

Try posting the contents of /proc/irqs and /proc/ioports, perhaps
someone here will see something you don't.

..Stu

Re: Serial Ports

[Ian D . Stewart]

On 2001.09.06 16:27:06 -0400 Stephen Torri wrote:

> 
> I have noticed that serial ports change IRQ to either 3 or 4. There is no
> reason for this behavior. I have created a perl script to create a log
> containing the irqs assigned and their ioports. Is there anything else I
> could log that might unmask the problem?
> 
> So far if the serials are assigned to IRQ 4 then the sync with the palm
> pilot doesn't work (/dev/pilot = /dev/ttyS0). If its IRQ 3 then it does.

As I understand it, /dev/ttyS0-3 are set to industry standard values on
startup (they are not probed).  The values can be changed using the
command-line utility setserial.  You can specify non-standard values in an
rc.serial conf file which will be read on startup.

The setserial manpage covers this is some detail.


HTH,
Ian

-- 
"God may have mercy.  We will not."
--Senator John S. McCain (R-AZ)

RE: Serial ports

[Naushit Sakarvadia]

> Does anyone have any ideas where I can go from here. I am not 
> 100% that the hardware is working so perhaps that could be the problem.

if you doubt your hardware then.. do this to test it.

first of all write a routine that countineously write "ox55" or "oxAA"
on the serial port. then check the pin no 2( i.e always transmit) and check
you should be gettinhg "squere wave" on that pin with respect to ground( i.e
pin 7)


-- Naushit 


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Serial ports

[Grant Carter]

Hi all

I posted a question a while ago to the list about not being able to get
the second serial port ttyS1 (on SMC2) working on my BSE-IP board
running the 2.2.5. The kernel finds the port but when I echo something
to it, nothing comes out of the port. I received some replies but
nothing that was suggested has worked. Could someone please suggest how
I can test the second serial port and then hopefully get it working.
Below are the things that I have tried so far:

I added SMC2 to the rs_table in arch/ppc/8xx_io/uart.c and the kernel
detected the port.
CPM UART driver version 0.02
ttyS00 at 0x0280 is a SMC
ttyS01 at 0x0380 is a SMC

I have made sure that there is the correct device nodes in /dev 
# ls -la ttyS*
crw-r--r--   1 root     0          4,  64 Sep  7  1998 ttyS0
crw-rw----   1 root     66         4,  65 Dec 10  1999 ttyS1

Does anyone have any ideas where I can go from here. I am not 100% that
the hardware is working so perhaps that could be the problem.

Many thanks in advance
Grant


-- 
Grant Carter                              gcarter@eng.uct.ac.za
Department of Electrical Engineering      University of Cape Town
Tel: +27 (0)21 650-3467                   Fax: +27 (0)21 650-3465
                     "Coffee not found - operator halted!"

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