Re: Serial driver problems with 2.1.120-pre3

Etienne Lorrain (lorrain@fb.sony.de)
Wed, 2 Sep 1998 13:59:12 +0001

Richard Gooch <rgooch@atnf.csiro.au> wrote:
> Hi, all. I've just tried 2.1.120-pre3 and I've noticed an unpleasant
> interaction with setserial v2.14. If I do:
>
> # setserial /dev/ttyS0 auto_irq skip_test autoconfig
> # setserial /dev/ttyS1 auto_irq skip_test autoconfig
> # setserial -bg /dev/ttyS0 /dev/ttyS1
> /dev/ttyS0 at 0x03f8 (irq = 0) is a 16550A
> /dev/ttyS1 at 0x02f8 (irq = 0) is a 16550A

Hi,

I do not know if it is related to 2.1.120-pre3, but this
can appear if the two serial ports are on the same IRQ, or
if another board maintains the IRQ line active.
Also, you have a two processor machine, the two "setserial"
may be done in parallel - not nice for IRQ probing...

Why did you add the "skip_test" option ?

What happens if you compile the kernel with "SERIAL_DETECT_IRQ"
(then the driver initialise all serial ports - and clear IRQ lines -
*before* autodetecting the IRQs, and does that sequencially for
each lines).

Then you can remove the setserial lines from your startup scripts,
probing for IRQ is basically unsafe but it is better to do that
at kernel startup than when a lot of tasks are running in 'init'.
The safest is always to do "setserial /dev/ttyS0 irq 4".

> Does anybody have any idea what's going on here?

Just ideas... nothing as interresting as a Penguin beer!

Etienne.

--
-- The world belong to its organizer.


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