[SLL] trouble with extra serial ports. doesn't look like irq problems...

[Robert Woodcock]

On Mon, May 02, 2005 at 11:21:00AM -0700, Ben Johnson wrote:
> #from dmesg:
> Serial: 8250/16550 driver $Revision: 1.90 $ 48 ports, IRQ sharing enabled
> ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
> ttyS1 at I/O 0x2f8 (irq = 3) is a 16550A
> ttyS2 at I/O 0x3e8 (irq = 4) is a 16550A
> ttyS3 at I/O 0x2e8 (irq = 3) is a 16550A
> 
> I don't know how to tell what kind of bus these ports are on.  (ISA or
> PCI?)  they're soldered onto the main board, which makes me think ISA.
> even so, I think all my IRQ debugging would have taken care of the
> typical ISA issues.

Anything with such a low I/O port number is almost certainly ISA. However,
that's what Linux thinks it found and not necessarily what's actually there.

PCI is plug-n-play. Anything PCI would show up (with the *correct* I/O port)
in lspci output. Check that, and if you see something there, use setserial
to update Linux's I/O port settings for ttyS2 and ttyS3.

The chips used for any peripheral would be different for hooking up to the
ISA bus vs. the PCI bus. Googling the chip part number will often dig up a
PDF which will tell you.
-- 
Robert Woodcock - rcw at blarg.net
perl -e '$a-=($_%4-2)*4/$_++while++$_<2e6;print"$a\n"'