[U-Boot] SUNXI: A64: Increase SPL size

[Jagan Teki]

Hi Andre,

On Thu, Nov 9, 2017 at 3:36 AM, André Przywara <andre.przywara at arm.com> wrote:
> On 08/11/17 19:59, Jagan Teki wrote:
>> Hi,
>>
>> I'm trying to increase SPL size to 64K(with SRAM A2), so-that SPL can
>> able to fit new features like falcon. I knew the limit about 32K but
>> page[1] stating that we can use approximately 192 KiB of contiguous
>> SRAM.
>
> We are not really sure about this. The memory following SRAM A1 is
> called SRAM C (not A2, that is secure memory at 0x44000). And this is
> actually meant for use by the DisplayEngine, AFAIK. We found it unstable
> to use from the ARM cores. With the default config is it not even
> covering the whole region as described in the manual.

>> eGON.BT0 has limit of reading 32KB, Can't we use > 32KB SPL here?
>
> Well, how? As far as I know the *BROM* does not load more than 32KB, at
> least not with the ("un-encrypted") eGON.BT0 format. Or could you
> actually load more code?

Yes, I've 40K SPL start from sector 16 of SD Since BROM load 32KB to
A1 and I had an impression of using SRAM C for > 32KB. So BROM only
have an access to A1 (not any other SRAM's like SRAM C) we can't
increase the SPL size > 32KB..this is strict. correct?

>
> I *think* we can load more with the "secure" payload, which requires the
> "secure boot" fuse to be burned (with no return), which in turn will let
> the BROM refuse to load a standard eGON.BT0 Boot0/SPL, but only the
> secure packaged version (TOC0): http://linux-sunxi.org/TOC0

Did you try this? if yes please point the same.

>
>> because I've tried with 64K SPL size with existing SPL code and was
>> able to boot, but with increasing SPL by enabling falcon seems like
>> BROM unable read eGON.BT0 which eventually booting failed. Any inputs?
>
> So why do you need falcon, desperately? You can put the kernel into the
> SPL FIT image (u-boot.itb), then have the U-Boot proper just execute
> booti (no further loading). That works from SPI flash, also. If you are
> really want to, you can disable USB, Ethernet and the timeout and save
> some time here. But those are .config options and shouldn't require code
> changes.

Falcon make direct Linux boot, from SPL. we can skip U-Boot, (even
ATF). I'm not using USB, ethernet on SPL so current code look fit with
what SPL wants.

thanks!
-- 
Jagan Teki
Free Software Engineer | www.openedev.com
U-Boot, Linux | Upstream Maintainer
Hyderabad, India.