Hi Heiko,
On Thu, 25 Apr 2019 at 03:00, Heiko Stuebner heiko@sntech.de wrote:
Hi Simon,
Am Donnerstag, 25. April 2019, 00:26:28 CEST schrieb Simon Glass:
On Thu, 18 Apr 2019 at 10:47, Heiko Stübner heiko@sntech.de wrote:
Am Donnerstag, 18. April 2019, 08:35:49 CEST schrieb Philipp Tomsich:
Simon,
On 18.04.2019, at 06:32, Simon Glass sjg@chromium.org wrote:
Hi Kever,
On Mon, 1 Apr 2019 at 02:21, Kever Yang kever.yang@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.
and maybe for a broader functionality description, something needs to load things like ATF via a FIT image from a mmc for example. (which needs FIT code and also real mmc drivers).
And as we experienced on rk3288 as well recently, SRAM may be very well too small to accomplish that, so TPL needs to init the sdram separately to make room for the code needed to get ATF up and running, which must be done before jumping into proper uboot.
I have to ask what the boot ROM is buying us? U-Boot TPL/SPL can load programs itself without the boot ROM and its size limit. Why not just stop using the boot ROM on these devices?
The problem is more that the sram is to small to hold mmc + fit + everything else. So we need at least on some socs bootrom -> tpl (in sram) -> sdram init -> bootrom -> spl (in ddr) (1) -> load fit with u-boot and atf binaries -> jump to ATF -> jump to uboot or in falcon mode for vyasa for example (2) -> load linux directly -> jump to Linux
But my understanding is that RK3399 has 192KB of SRAM. How much do you need? That should be plenty for SPL?
Regards, Simon