[U-Boot] [PATCH 1/3] rockchip: rk3399: add tpl support

[Philipp Tomsich]

Simon,

> On 18.04.2019, at 06:32, Simon Glass <sjg at chromium.org> wrote:
> 
> Hi Kever,
> 
> On Mon, 1 Apr 2019 at 02:21, Kever Yang <kever.yang at rock-chips.com> wrote:
>> 
>> Rockchip platform suppose to use TPL(run in SRAM) as dram init and
>> SPL(run in DDR SDRAM) as pre-loader, so that the SPL would not be
>> limited by SRAM size.
>> This patch add rk3399-board-tpl.c and its common configs.
> 
> So this means that TPL inits SDRAM? That seems strange to me...why
> have SPL at all, then? What is SPL supported to do on RK3399
> platforms?

For TPL->SPL implementation on Rockchip, we generally rely on the BootROM
to load the TPL stage (to SRAM) and the SPL stage (to the start of DRAM).  The
BootROM usually limits the size of the SPL stage, so we can’t use a full U-Boot
already.

Even more constricting are the TPL size constraints (as this seems to have originally
only been intended to be size-optimized DRAM init code) on some devices.

Hope this explains the situation,
Philipp.