IRQ on PCMCIA Modem

Hi everyone,

I'm trying to set up a PCMCIA modem ("Mercury 56k Fax Modem Card", FCC
ID 5HRTAI-31904-M5-E) to work on a Linux notebook with a customised
kernel 2.4.21. In principle, the Modem does work as /dev/ttyS1, but
it's extremely slow.auf einem System mit einem angepassten

Based on what I read in the PCMCIA Howto, the problem is most likely an
interrupt conflict:

| If the modem seems to work only very, very slowly, this is an almost
| certain indicator of an interrupt conflict.

However, at the moment, the modem seems not to use and interrupt but is
"working" in polled mode (IRQ 0):

[root@eclipse pcmcia] setserial /dev/ttyS1
/dev/ttyS1, UART: 16550A, Port: 0x02f8, IRQ: 0

This is most likely the main reason of my problem. From the PCMCIA-Howto:

| ... try using setserial to change the irq to 0, and see if the modem
| works. This causes the serial driver to use a slower polled mode
| instead of using interrupts.

I think I should also mention the output of cardctl, where no IRQ is
shown for the modem in socket 1:

[root@eclipse pcmcia] cardctl config
Socket 0:
Vcc 3.3V Vpp1 3.3V Vpp2 3.3V
interface type is "cardbus"
irq 10 [exclusive] [level]
function 0:
Socket 1:
Vcc 5.0V Vpp1 0.0V Vpp2 0.0V
interface type is "memory and I/O"
speaker output is enabled
function 0:
config base 0x0100
option 0x61 status 0x08 ext 0x00
io 0x02f8-0x02ff [8bit]

So I have two questions:

- How can I find a free IRQ? Is this just by looking for missing entries
in /proc/interrupts? What irritated me a bit was that /dev/ttyS0 is on
IRQ 4 (setserial) but not shown upon cat /proc/interrupts.

- On a RedHat system, how do I assign the free IRQ I found to the modem
correctly? Trying to change SERIAL_OPTS in /etc/pcmcia/serial.opts was
not very successful (I could get the modem to use anIRQ but it did not
work anymore).

Thanks in advance,

Guenter

In comp.os.linux.portable Guenter Resch <spambox@telering.at> wrote:
[color=blue]
> [root@eclipse pcmcia] setserial /dev/ttyS1
> /dev/ttyS1, UART: 16550A, Port: 0x02f8, IRQ: 0[/color]

My first guess is that you've configured your kernel with CONFIG_ISA
disabled. Enable that and try again.

-- Dave

[email]dhinds@sonic.net[/email] wrote ...[color=blue]
> In comp.os.linux.portable Guenter Resch <spambox@telering.at> wrote:
>[color=green]
>> [root@eclipse pcmcia] setserial /dev/ttyS1
>> /dev/ttyS1, UART: 16550A, Port: 0x02f8, IRQ: 0[/color]
>
> My first guess is that you've configured your kernel with CONFIG_ISA
> disabled. Enable that and try again.[/color]

Unfortunately, enabling CONFIG_ISA did not change the situation.

When start with empty SERIAL_OPTS in /etc/pcmcia/serial.opts, the
modem is still running in polled mode (IRQ 0), when I force it to use
either IRQ 3 or 5 (SERIAL_OPTS="irq 5"; only one serial and parallel
port present on the system, so these two should be free), I get an
output like this:

[root@eclipse root] setserial /dev/ttyS1
/dev/ttyS1, UART: 16550A, Port: 0x02f8, IRQ: 5

[root@eclipse root] cardctl config
Socket 0:
Vcc 3.3V Vpp1 3.3V Vpp2 3.3V
interface type is "cardbus"
irq 10 [exclusive] [level]
function 0:
Socket 1:
Vcc 5.0V Vpp1 0.0V Vpp2 0.0V
interface type is "memory and I/O"
speaker output is enabled
function 0:
config base 0x0100
option 0x61 status 0x08 ext 0x00
io 0x02f8-0x02ff [8bit]

However, wvdial tells me that the modem does not respond when I'm trying
to use /dev/ttyS1 :-(

Any more suggestions what to try?

Guenter

[email]dhinds@sonic.net[/email] wrote:[color=blue]
> In comp.os.linux.portable Guenter Resch <spambox@telering.at> wrote:
>
>[color=green]
>> [root@eclipse pcmcia] setserial /dev/ttyS1
>> /dev/ttyS1, UART: 16550A, Port: 0x02f8, IRQ: 0[/color]
>
>
> My first guess is that you've configured your kernel with CONFIG_ISA
> disabled. Enable that and try again.[/color]

Many thanks, Dave

You just helped cure my problems with a PCMCIA NIC under kernel 2.4.22

Who would'a thought that a laptop with /just/ PCMCIA slots would need /ISA/
support for PCMCIA devices? Certainly not me <grin>.

--
Lew Pitcher

Master Codewright and JOAT-in-training
Registered Linux User #112576 ([url]http://counter.li.org/[/url])
Slackware - Because I know what I'm doing.

Guenter Resch <spambox@telering.at> wrote:[color=blue]
> [email]dhinds@sonic.net[/email] wrote ...[/color]
[color=blue][color=green]
>> My first guess is that you've configured your kernel with CONFIG_ISA
>> disabled. Enable that and try again.[/color][/color]
[color=blue]
> Unfortunately, enabling CONFIG_ISA did not change the situation.[/color]

If you had to enable CONFIG_ISA then it seems unlikely that you also
have another problem. Are you sure you installed the new kernel after
reconfiguring and rebuilding? Double check with "uname -a".
[color=blue]
> When start with empty SERIAL_OPTS in /etc/pcmcia/serial.opts, the
> modem is still running in polled mode (IRQ 0), when I force it to use
> either IRQ 3 or 5 (SERIAL_OPTS="irq 5"; only one serial and parallel
> port present on the system, so these two should be free), I get an
> output like this:[/color]

You cannot change the interrupt assignment for a PCMCIA device with
setserial. It tells the serial driver to use that irq, but it does
not reconfigure the PCMCIA socket. Thus, it won't ever work.

-- Dave

[email]dhinds@sonic.net[/email] wrote ...[color=blue][color=green]
>> Unfortunately, enabling CONFIG_ISA did not change the situation.[/color]
>
> If you had to enable CONFIG_ISA then it seems unlikely that you also
> have another problem. Are you sure you installed the new kernel after
> reconfiguring and rebuilding? Double check with "uname -a".[/color]

Yes, the newly compiled kernel was enabled ... I had already checked
before. Nevertheless, it was great you said that because it made me
check the whole thing with the RedHat standard kernel ... and guess
what, ttyS1 got IRQ 3 assigned without passing on any SERIAL_OPTS. I
just have to check at home if the modem really works ...

If it does, I only need to find out what option I disabled in my custom
kernel that is causing this problem ... hints, anyone?

Regards,

Guenter

Guenter Resch wrote ...[color=blue]
> If it does, I only need to find out what option I disabled in my custom
> kernel that is causing this problem ... hints, anyone?[/color]

The problem was CONFIG_PNP disabled ... I just assumed that not to be
neccessary for PMCIA as my PCMCIA NIC did very well with it. Thanks for
these useful hints,

Guenter

Guenter Resch <spambox@telering.at> wrote:[color=blue]
> Guenter Resch wrote ...[color=green]
>> If it does, I only need to find out what option I disabled in my custom
>> kernel that is causing this problem ... hints, anyone?[/color][/color]
[color=blue]
> The problem was CONFIG_PNP disabled ... I just assumed that not to be
> neccessary for PMCIA as my PCMCIA NIC did very well with it. Thanks for
> these useful hints,[/color]

Hmmm, I do not see why this would make any difference.

-- Dave

Hi,

did you check whether you have ISA support enabled in your kernel?
On my old Compaq 1130T, which has no cardbus slots but 16-bit PCMCIA,
So if it is a pcmcia 16bit this might be the reason.

I once forgot to compile in ISA support and no cards worked.
I am not so sure about PNP, I havent enabled CONFIG_ISA and
CONFIG_ISAPNP in my kernel and it works fine with network, modem, wlan.

The IRQs on PCMCIA are assigned by cardmgr, AFAIK, ISAPNP has nothing to
do with it, but if you enable ISAPNP, you´ll probably enable ISA too and
so it works ...

Greetz,
Lutz