Trouble with SMC serial port in ppc/boot/simple on Embedded Planet 8248 board

[Laurent Pinchart]

Hi everybody,

I'm trying to port the Linux kernel (2.6.15.1) to the Embedded Planet 8248 
board. The board has a proprietary boot loader and uses SMC1 has a serial 
console.

After some work (2.6.15.1 has a nasty bug related to relocation which has been 
fixed in the git tree), I have been able to load and start the kernel image.

Unfortunately, the early serial output is lost. Here is the kernel boot 
messages I get with 2.6.15.1 :

-----------------------------------------------------------------------------
Embedded Planet EP8248 PowerPC port
Built 1 zonelists
Kernel command line: console=ttyCPM0,9600n8 root=/dev/ram0 rw
PID hash table entries: 4096 (order: 12, 65536 bytes)
Warning: real time clock seems stuck!
Dentry cache hash table entries: 131072 (order: 7, 524288 bytes)
Inode-cache hash table entries: 65536 (order: 6, 262144 bytes)
Memory: 777088k available (1520k kernel code, 440k data, 96k init, 0k highmem)
Mount-cache hash table entries: 512
NET: Registered protocol family 16
-----------------------------------------------------------------------------

And here is the same with the modified 2.6.10-pre3 kernel shipped with the 
board:

-----------------------------------------------------------------------------
loaded at:     00200000 002D01E8
relocated to:  00400000 004D01E8
board data at: 004CE12C 004CE168
relocated to:  0040509C 004050D8
zimage at:     00405A31 004CD2C4
avail ram:     004D1000 01000000

Linux/PPC load: console=ttyCPM0,9600n8 root=/dev/ram0 rw
Uncompressing Linux...done.
Now booting the kernel
Linux version 2.6.10-rc3 (laurent at pclaurent) (gcc version 3.4.1) #5 Thu Jan 19 
15:25:42 CET 2006
Embedded Planet EP8248 PowerPC port
Built 1 zonelists
[...]
-----------------------------------------------------------------------------

Early boot messages (printed with puts in ppc/boot/simple/misc-embedded.c) are 
lost.

I compared the Embedded Planet kernel with the 2.6.10-rc3 from kernel.org, 
haven't seen any big change related to the SMC serial port. Embedded Planet 
uses BRGC7 instead of BRGC1 for SMC1, but that didn't work better for me.

I of course enabled the RS232 transceivers in the board control and status 
registers (BCSR).

Could anyone give me any pointer to where I should look at ?

Thanks in advance,

Laurent Pinchart