[Gta04-owner] successful boot from usb

Andreas Kemnade andreas at kemnade.info
Mon Nov 20 12:40:07 CET 2017

On Mon, 20 Nov 2017 09:06:56 +0100
"H. Nikolaus Schaller" <hns at goldelico.com> wrote:

> > Am 20.11.2017 um 07:40 schrieb Andreas Kemnade <andreas at kemnade.info>:
> > 
> > On Sun, 19 Nov 2017 13:28:34 +0100
> > Andreas Kemnade <andreas at kemnade.info> wrote:
> >   
> >> On Sat, 18 Nov 2017 23:29:32 +0100
> >> Andreas Kemnade <andreas at kemnade.info> wrote:
> >>   
> >>> Hi,
> >>> 
> >>> I have hacked the pusb tool a bit so that I could use it to boot the
> >>> gta04. The original pusb tool seems to work only at the right moon
> >>> phase, the gta04 oriented exactly in north-south direction ;-)
> >>> 
> >>> Now I am a quit independant of that.  
> >> 
> >> The results are here:
> >> https://github.com/akemnade/omap-u-boot-utils/
> >> 
> >> Now I just have to find out why I can only boot the old SLO that way
> >> (on A4).  
> > 
> > 
> > Well, I found the reason.
> > 1. There is MLO and spl/u-boot-spl.bin
> > The further has a CHSETTINGS header which can configure things like
> > image start address. This header cannot be used for peripheral boots like
> > serial or usb, only for flash/mmc boots. So the image start address has to stick
> > to the standard.  
> Ok, this means that MLO is a special variant only.
> But did I understand it correctly, we have to strip the headers from spl/u-boot-spl.bin
> to make it an image for serial/usb boot?
Other way round.
MLO = CHSETTINGS (and other) + spl/u-boot-spl.bin

so, MLO is for nand/mmc and spl/u-boot-spl.bin is for serial/usb.

But SPL_TEXT_BASE (used e.g. in linker script) has to be set to default position because serial/usb cannot know

> If we understand that and have a script that does it, we can automatically add
> such images to:
> http://download.goldelico.com/letux-u-boot/GTA04-OneNAND/latest/
Well, what I do not understand yet: the reasons for the different SPL_TEXT_BASE settings.
And if using a SPL_TEXT_BASE which is compatible with serial boot/usb also is ok for mmc.

Maybe we need a separate config serial/usb (or maybe only for usb to avoid mmc/nand code in favour
of DFU code). BTW: I need to look at boot order stuff anyways:
What was the reason for the separate onenand config?

> > 
> > After I changed that base address, I could load a recent spl from usb.
> > I managed to load uboot via ymodem (not that strange kermit anymore) via rs232.
> > Next step would be to enable dfu in spl. There is an option in uboot for that.
> > But I do not manage to compile u-boot that way.
> > 
> > But what can be more easily managed: Compile dfu into main uboot (well,
> > you have to first enable the dfu command, then you can open the dfu menu in uboot menuconfig),
> > so it can be enabled on a button in the menu.
> > Access to mmc and to ram seems to work, access to onenand cannot be enabled.
> > But with dfu to ram, you can e.g. load kernel, fdt and a ramdisk and a script to ram.
> > Or load other things to ram and flash it to nand using that script.
> > So with that you can basically do a lot of things.  
> Wow, cool work!
> If you have patches for our u-boot git (that do not break OMAP4 & OMAP5), we can integrate them.
For the dfu in main u-boot it should be not critical,
dfu in uboot is only started via a command, so if not used, it will not harm.

I'll put them in separate branches.

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