[U-Boot] SPL Dfu update

[Tom Rini]

On Wed, Oct 30, 2013 at 03:34:45PM +0100, Michael Trimarchi wrote:
> Hi
> 
> On Wed, Oct 30, 2013 at 3:24 PM, Stefano Babic <sbabic at denx.de> wrote:
> > Hi Otavio,
> >
> > On 30/10/2013 15:19, Otavio Salvador wrote:
> >
> >>> OMAP4/3 can boot over the otg, so you can send MLO and let it wait for the
> >>> second stage boot. We have already SPL USBETH in u-boot but in production
> >>> otg flashing can be very useful. Think SPL as a differently configured U-BOOT
> >>> doesn't change the problem but yes it's a nice idea.
> >>
> >> But you'd usually want to have an 'upgrade mode' which allows DFU to
> >> run. In this case, this could be done using complete U-Boot instead of
> >> SPL, no? In case customer needs a slim version of it, it could be
> >> accomplished using a specific config and having:
> >>
> >> SPL
> >> Update mode U-Boot (normal U-Boot with less features)
> >> Complete U-Boot (interactive and like)
> >>
> >> or am I missing something?
> >
> >
> > Right, I agree completely with you.
> >
> > That's the reason I do not understand why we have to push DFU into SPL.
> > Maybe we both are missing something.
> 
> It's simple:
> 
> - first stage boot can be sent over the otg
> - using dfu to flash the u-boot.img, kernel .. etc
> 
> dfu is another way to upload and write second stage or what you want. I don't
> see the point to don't have this option. We have merged USBETH spl support
> and dfu is more useful.
> 
> ./usb_load MLO.flash
> ./dfu-util ... MLO
> ./dfu-util ... u.boot.img
> ..
> ./dfu-util -R

Right.  The point of USBETH is to continue the flow from ROM in cases
where we're already sending the initial payload this way.  It would be
analogous to adding support for the USB mode omap3+ support to SPL so
that you do:
./usb_load MLO.flash u-boot-flash.img
./dfu-util ... MLO
..
./dfu-util -R

All of that said, I wouldn't mind seeing how the code to make a DFU loop
looks, but you're likely to run into the problem of (per Wolfgang) SPL
needing to move stack pointerinto DDR once DDR is up so that you have
environment, and all of the other big stack users functional.

-- 
Tom
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