# RE: Configure 8xx\_io in 2.4.21-pre3

- From: James Don \<hidden\>
- Date: 2003-01-14 18:02:02 
- List: linuxppc-dev
- Page: https://ratatoskr.run/linuxppc-dev/2003/01/9386247
- Thread: https://ratatoskr.run/linuxppc-dev/2003/01/9386247/t.md

```text

Wish I could help ... I have been mostly using a mvista source tree
though...

And I have never tried to switch kernel versions yet ;-)

Jim

-----Original Message-----
From: Xiaogeng (Shawn) Jin [mailto:<redacted>]
Sent: Tuesday, January 14, 2003 12:59 PM
To: James Don
Cc: <redacted>
Subject: Re: Configure 8xx_io in 2.4.21-pre3

Hi Jim,

Thank you for your suggestions. I had a working 2.4.4 (released by DENX)
kernel on my board, which has more stuff related to 8xx_io than
2.4.21-pre3. I don't know if those DENX-added stuff are necessary to
enable 8xx CPM or if the 8xx_io code in 2.4.21 is sufficient to make 8xx
CPM working. Probably I need to compare the code in these two versions
line by line.

- Shawn.

> 1.) I recommend start with UART only build of the kernel first
>
> 2.) Did you check that your PA,PB,PC, and PD pins are set up properly ...
>
> I my custom board had pins moved for things like enet on SCC ? However
> normally I believe SMC1 only can be on one pair of pins for a UART ...
> another
>
> 3.) Another thing to look at is your BRG clock for your board ... in my
> kernel I found mvista didn't look at the some parts of the hardware reset
> word that divide down my 80 Mhz reference intenerally before it goes to
the
> brg ... I was really surprised this code wasn't there ...

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```