[U-Boot] Booting Wandboard through USB

[Tom Rini <trini@konsulko.com>]

On Sat, May 30, 2015 at 01:09:48PM -0700, Eric Nelson wrote:
> On 05/30/2015 10:24 AM, Vincent Stehl? wrote:
> > On 05/30/2015 06:49 PM, Tom Rini wrote:
> > ..
> >> The second would be trying to "fake" things such that for 
> >> imx_usb_loader you can pass both SPL and u-boot.img, and SPL is 
> >> run, inits memory and just exists and then u-boot.img is loaded
> >> and run, similar to how with the non-SPL case you can use the
> >> loader to pass in u-boot.imx as well as a kernel, ramdisk, etc,
> >> into DDR.
> > 
> > I wonder if we could use the i.MX6 ROM "plugin"[1] mechanism with u-boot
> > SPL, to download it through USB, have it configure the DDR and return to
> > the ROM, in a way that would allow us to resume downloading the second
> > stage u-boot through USB...
> > 
> > Best regards,
> > 
> > V.
> > 
> > [1] Chapter "8.8 Plugin Image" of the i.MX6D/Q Reference Manual.
> 
> ;) This is an even older idea:
> 	http://lists.denx.de/pipermail/u-boot/2012-September/thread.html#134444
> 
> In my earlier e-mail, I said that this was more complicated because
> it involves hacking the image creation process (and perhaps some
> linker scripts).
> 
> It also requires that SPL images have some form of flag telling them
> not to boot, but return to the ROM boot loader after initializing DDR
> (i.e. they need to optionally act like a plugin).

Well there is precendce these days for doing special things to cooperate
with ROM, we do something not totally dissimilar for sunxi I believe, in
some cases.

-- 
Tom
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