[U-Boot] Booting Wandboard through USB

[Eric Nelson <eric.nelson@boundarydevices.com>]

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Hi Tom,

On 05/30/2015 12:25 PM, Tom Rini wrote:
> On Sat, May 30, 2015 at 10:41:16AM -0700, Eric Nelson wrote:
>> On 05/30/2015 09:49 AM, Tom Rini wrote:
>>> On Fri, May 29, 2015 at 11:46:40AM +0200, Vincent Stehl?
>>> wrote:
>>> 
[...]
>> 
>> This is an old topic and the threading seems to be messed up in
>> the archive, but I think Michael Trimarchi has a solution based
>> on inclusion of DFU in the SPL image:
>> 
>> http://lists.denx.de/pipermail/u-boot/2013-October/165849.html
>> 
>> I would prefer to see something slimmer if possible, and using 
>> imx_usb has the advantage of only needing a single tool on the 
>> programming host.
> 
> Ah yes, firing up and letting DFU do the rest is another option I
> had forgotten about.  But I too lean towards something imx_usb can
> do as that will also make integration into the Freescale factory
> flashing tool easier I suspect.
> 

I think there's an easy way and a more complicated way to do this.

The easiest is probably to do something custom in SPL and
update imx_usb to support the same.

There's a WRITE_FILE command in the serial download protocol
which could serve as an example, though 100% compatibility isn't
needed, since the internal ROM isn't needed.

Note that this would also require updates to the SB_LOADER tool
used in the Freescale Manufacturing tool for use on Windows.
I think that's closed source (and C# or somesuch), but perhaps
Fabio can provide details.

The harder way (and the Freescale way) is to somehow package
the SPL content and full U-Boot image in a way such that the
SPL is a "plugin" that can execute and return to the boot loader
after setting up DDR and bundle SPL and u-boot.img into a
single .imx file.

I think that both imx_usb and sb_loader support plugins.

Regards,


Eric


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