[Letux-kernel] MIPS-Generic Kernel on CI20

[H. Nikolaus Schaller]

Hi,

I have spent some minutes to look at what we need to
boot the mips-generic kernel on the CI20.

Of course we initially need to enable U-Boot to load the FDT
from µSD and modify the memory size etc.

For the CI20 U-Boot we have two options:

a) modify the CI20 U-Boot that is working to add (optional)
FDT loading. It is a special CI20 only U-Boot 2013.10:

https://git.goldelico.com/?p=letux-uboot.git;a=shortlog;h=refs/heads/ci20-v2013.10

The binaries we usually install through makesd are here:

https://download.goldelico.com/letux-u-boot/CI20/latest/

A drawback of this approach is that the U-Boot.img itself is
not stored in a first partition of the µSD, rather at a fixed
location the SPL knows about. This makes modifying/improving the
U-Boot more difficult.

b) configure the x1600/x2000 U-Boot 2013.07 which already has the
FDT additions in code for the CI20 and uses a dual-partition scheme.

https://git.goldelico.com/?p=letux-uboot.git;a=shortlog;h=refs/heads/ingenic-x1600-v4

There we find a a config option and include/configs/ci20.h.

I had to tweak the latter a little to get it compiled (patches included
above). There are some tools to add a LOGO bitmap as ELF-Linux binaries
only in the source tree and they failed to recompile from source. And I
had to change the CONFIG_SYS_UART_INDEX to 4.

But I only get this from SPL on the 115200 bps console...

b$@ᇤ夆ąFĤĄ䥧bb$@ᇤ夆̅FĬĄ䥧bʅdeĄB

Binaries: https://download.goldelico.com/letux-u-boot/CI20-new/latest/

Some preliminary conclusions:
- it is indeed possible to compile some CI20 SPL that is doing something after boot from µSD
- the CI20 support in 2013.07 may have never been tested and has bugs
- or I have to adjust some more configs
- or some x1600/x2000 patches in this tree have damaged the CI20 setup (CGU?)

Generally I tend to go path b) and debug because then we have a single
U-Boot tree for all Ingenic/Lumissil devices.

What do you think?

BR,
Nikolaus