[U-Boot] [PATCH 5/5] MX5:MX53: add initial support for MX53EVK board

[John Rigby]

On Sun, Dec 19, 2010 at 10:19 PM, Jason Liu <liu.h.jason at gmail.com> wrote:
> Hi, Stefano,
>
> 2010/12/17 Stefano Babic <sbabic at denx.de>:
>> On 12/17/2010 04:05 AM, Jason Liu wrote:
>>> There is pretty much different with I.MX51 ROM,  we will not use DCD
>>> data file to config the
>>> DDR script since ROM has the DCD size limitation and use the advance
>>> feature of what we
>>> called plug-in,  the plug-in code must be in the first 2K of MMC card
>>> from 0x400 offset, that's
>>> why we need put this code section before start.S. The plug-in code
>>> will be called by boot ROM
>>> to do DDR init first and copy u-boot to DDR and jump to _start  to run it.
>>
>> As I am not understanding what you mean as "plugin", it seems to me you
>> need some code able to set-up RAM and copy the u-boot code. This method
>> looks like very similar to other SoCs, where a first stage boot loader
>> is needed or when we boot from NAND.
>
> Forget about the case about boot From NAND, we are talking about boot
> from SD/MMC card here.
> Why I call it here"plug-in", it due to it use the plugin feature of ROM.
>
> This section of code is for ROM to load and run, thus it should meet
> the ROM boot structure requirement.
> The plugin feature of ROM can give more flexibility and it can
> overcome some shortcomings of DCD(used on mx51).
>
> By using this plugin we can get around the following issues:
> 1.      DCD size limitation issue, plugin can be the size of OCRAM free space region.
> 2.      Safe environment to re-configure PLL1 (without impacting SDRAM) as
> the plugin runs from OCRAM.
>
>

Jason:
No one is arguing about the use the plugin feature.  The objection is
to how you are getting the plugin bits into the u-boot image.  You
should use a tool to prepend the plugins to the u-boot.bin file in a
similar way to how mkimage is used for i.mx51 and others.

Stefano:
I know Freescale has a binary to do this but I don't believe the
source is available.  The binary is included as a package in the
i.mx28 BSP as well as some sample plugins.

You can find your way to the i.mx28 page by googling
"site:freescale.com i.mx28 BSP" and following the top most hit.  You
have to register to download the BSP.

Once you download the BSP you will find a source archive called
L2.6.31_10.08.01_SDK_source.tar.gz.

The sample plugin package is in the archive in a file called
L2.6.31_10.08.01_SDK_source/pkgs/imx-bootlets-src-10.08.01.tar.gz.  I
guess bootlets are another name for plugins.

The binary utility for creating bootlets from elf files is called
elftosb-0.4.tar.bz2 in the same archive.  The utility appears to be a
typical over engineered c++ pile of stuff.  One would think that you
could accomplish the same thing with objdump, and a patch to mkimage.

Chapter 12 of the i.mx28 Technical Reference Manual describes this, I
have not seen a doc for i.mx53 yet and am just assuming that it is the
same as i.mx28.
http://cache.freescale.com/files/dsp/doc/ref_manual/MCIMX28RM.pdf

br,

John