[U-Boot] [PATCH] arm: socfpga: control reboot from SRAM via env callback

[Marek Vasut]

On 5/3/19 10:53 PM, Simon Goldschmidt wrote:
> 
> 
> Marek Vasut <marex at denx.de <mailto:marex at denx.de>> schrieb am Fr., 3.
> Mai 2019, 22:42:
> 
>     On 5/3/19 10:39 PM, Simon Goldschmidt wrote:
>     >
>     >
>     > On 03.05.19 22:35, Marek Vasut wrote:
>     >> On 5/3/19 10:30 PM, Simon Goldschmidt wrote:
>     >>>
>     >>>
>     >>> On 03.05.19 22:28, Marek Vasut wrote:
>     >>>> On 5/3/19 10:08 PM, Simon Goldschmidt wrote:
>     >>>>> This moves the code that enables the Boot ROM to just jump to SRAM
>     >>>>> instead
>     >>>>> of loading SPL from the original boot source on warm reboot.
>     >>>>>
>     >>>>> Instead of always enabling this, an environment callback for the
>     >>>>> env var
>     >>>>> "socfpga_reboot_from_sram" is used. This way, the behaviour can be
>     >>>>> enabled
>     >>>>> at runtime and via saved environment.
>     >>>>>
>     >>>>> Signed-off-by: Simon Goldschmidt
>     <simon.k.r.goldschmidt at gmail.com
>     <mailto:simon.k.r.goldschmidt at gmail.com>>
>     >>>>
>     >>>> Would that be like a default "reset" command action ?
>     >>>> This probably shouldn't be socfpga specific then.
>     >>>
>     >>> No, it's a thing that lives on and influences even the soft
>     reset issued
>     >>> by linux "reboot" command. This is something *very* socfpga
>     specific.
>     >>
>     >> Hmmm, so isn't this a policy to be configured on the Linux end ?
>     >
>     > Might be, but it affects U-Boot's 'reset' command as well. And I guess
>     > it's set up in U-Boot this early to ensure it always works.
> 
>     Drat, that's right. So there has to be some way to agree on how the
>     reset works between the kernel and U-Boot ?
> 
>     > If it were for me, we could drop writing this magic altogether. I just
>     > figured some boards might require it to be written somewhere, and came
>     > up with a patch that might save those boards with the way it was
>     before.
> 
>     Isn't this magic actually used by bootrom ?
> 
> 
> Right. It tells the boot rom to jump to ocram on next reboot instead of
> loading spl from qspi or mmc. But if that's required or not a good idea
> at all depends on many factors. Some of them board related, some U-Boot
> related and some Linux related (depending on the hardware and drivers used).

Should that be runtime configurable then ?

-- 
Best regards,
Marek Vasut