[MVEBU] SPI flash offset was depecrated?

[Tony Dinh]

Hi Pali,

"flash u-boot.bin or spl.bin separately"

That's what we used to do many years ago! glad that we have a single
flashable image now, much more robust. Thanks for a clear and detailed
explanation!

Tony

On Sat, Jul 30, 2022 at 3:41 PM Pali Rohár <pali at kernel.org> wrote:
>
> On Saturday 30 July 2022 15:13:05 Tony Dinh wrote:
> > Hi Stefan and Pali,
> >
> > Sorry the question might be a bit trivial, but I could not find it in
> > the source tree. It's been a long time and I'm not up to date on this
> > subject. I recall a long time ago we needed to specify a SPI flash
> > offset for the u-boot image so SPL would know where to load it from.
>
> Hello! Now upstream U-Boot build process does not need to know offset
> where the proper U-Boot starts in SPI flash. SPL image determinate it at
> runtime (by looking into kwbimage header stored in SPI flash) and load
> proper U-Boot correctly.
>
> > I vaguely remember something about "return to BootROM and let the
> > BootROM load the u-boot image"? Is this applicable only when we kwboot
> > the u-boot-spl.kwb image, or also applicable to the u-boot payload on
> > SPI flash?
>
> Now upstream SPL can load proper U-Boot from SPI flash directly (if SPI
> flash driver is compiled into SPL) or it can "return to BootROM" and let
> BootROM to load proper U-Boot into RAM.
>
> This is configurable by defconfig options at compile time. We have
> tested that both options work fine. Using BootROM for loading U-Boot
> from SPI flash is slower than using dedicated SPL drivers (probably
> because BootROM read SPI at lower speed). But SPI flash drivers increase
> SPL binary (usage of BootROM does not). So you can choose which option
> you want -- either smaller SPL binary or faster U-Boot loading and
> booting. To disable SPI flash drivers in SPL, just disable option
> CONFIG_SPL_SPI.
>
> UART booting requires BootROM for loading proper U-Boot. But now
> upstream U-Boot generates universal u-boot-spl.kwb image which can be
> either flashed into SPI flash or booted via kwboot tool.
>
> You should _always_ flash u-boot-spl.kwb image into SPI flash memory. It
> is combined image of SPL and proper U-Boot with Marvell kwbimage header
> (required by BootROM). So never flash u-boot.bin or spl.bin separately.
>
> > I saw Stefan flashing instruction in board/Marvell/db-88f6820-gp/README
> >
> > Update from original Marvell U-Boot to mainline U-Boot:
> > -------------------------------------------------------
> > The resulting image including the SPL binary with the full DDR setup
> > is "u-boot-spl.kwb".
> > To update the SPI NOR flash, please use the following command:
> > => sf probe; tftpboot 2000000 db-88f6820-gp/u-boot-spl.kwb;\
> > sf update 2000000 0 60000
> > ...
> >
> > But building this board I got 642K u-boot-spl.kwb. So perhaps the
> > instructions above are out of date, or 60000  meant to be just an
> > example to be adjusted to the real image size?
>
> 60000 should be there just "example" and you should replace it by real
> image size.
>
> > Could you point me in the right direction,  ie. which Kconfig option
> > deals with this at the moment, or is it automatically set when we
> > build MVEBU -boot-spl.kwb?
> >
> > Thanks,
> > Tony
>
> Default Kconfig options for u-boot-spl.kwb should produce flashable
> SPI NOR image. It is option CONFIG_MVEBU_SPL_BOOT_DEVICE_SPI.