Re: UART misbehaves under Linkstation/KuroBoxHG

Guennadi Liakhovetski
2007-08-08T20:30:50Z

On Wed, 8 Aug 2007, Oncaphillis wrote:

> Greetings,
>
> I'm trying to compile a 2.6.2x kernel on a Linkstation/KuroBox HG/ppc
> following instructions given under
> http://www.kurobox.com/mwiki/index.php/Kurobox_support_in_stock_2.6_kernels

Wow, congratulations! Not too many endevour into this land, and even fewer
succeed:-) You'd probably be better off asking this on linuxppc-dev, but
anyway...

> and get weired settings and errors from the serial device (UART 16550A).
>
> Under the 2.4.17 kernel provided by the Kurobox manufacturer it gets IRQS in
> the range of 137/138 under 2.6.22 for the linkstation it gets IRQS 17/18 and
> the serial device behaves fishy

That interrupt numbers are different as under 2.4 is correct, however, I
get 16 and 17 for ttyS0 and ttyS1 on a kuroboxHG, are you sure you're
getting 17 and 18?

> communication errors
>
> "to much work in IRQ 16"

And here you get IRQ 16, which indeed should be ttyS0. And ttyS0 is
connected to the power-management microcontroller (AVR). Wait, what
userspace are you running? Have you swapped ttyS0 and ttyS1 everywhere? in
/etc/inittab for example? Besides, if you are running any vendor provided
(or community) tools to handle the AVR - they use ttyS1 by default, as it
was under 2.4 ans under "traditional" 2.6, whereas the 2.6 mainline kernel
for kurobox/linkstation uses the traditional for these CPUs port
numbering. I think this is your problem. Some user-space programme(s) are
accessing wrong tty.

Thanks
Guennadi
---
Guennadi Liakhovetski