[U-Boot] [PATCH 6/7] configs: tinker: Enable SDRAM, SPL stack

[Kever Yang]

On 2019/9/18 下午1:25, Jagan Teki wrote:
> On Wed, Sep 18, 2019 at 10:36 AM Kever Yang <kever.yang at rock-chips.com> wrote:
>>
>> On 2019/9/17 下午2:10, Jagan Teki wrote:
>>> SPL sets up SDRAM while in its board_init_f()
>>> function, it is possible for the stack to move
>>> there before board_init_r() is reached.
>>>
>>> So it is required to reserve the stack for SDRAM,
>>> with a proper location and size otherwise any
>>> operations during SPL handoff would leads to failure.
>>>
>>> On, this particular context tinker-rk3288 SPL is
>>> failing to launch U-Boot proper on SDRAM due to
>>> lack of stack.
>> If no SPL_STACK_R, it should still use CONFIG_SPL_STACK when system
>> init, right?
> SPL_STACK vs SPL_STTACK_R would be different in their usage former is
> used to setup the stack during early while calling board_init_f but
> the later used to setup the stack (with DRAM base) while calling
> board_init_r. if CONFIG_SPL_STACK_R is defined, then at this point the
> stack and global_data are relocated to below CONFIG_SPL_STACK_R_ADDR.
>
> CONFIG_SPL_STACK_R_ADDR - 0x80000 (this would be as part of sdram map)
> CONFIG_SPL_STACK  - 0xff718000 (this address where SDRAM not been used)
>
> Since the issue, is due to launch U-Boot proper from mmc, the stack
> that SPL during that time was not set it up.

I think the root cause is: the master of emmc controller can no access 
SRAM, and the emmc init
driver needs to use memory based on CONFIG_SPL_STACK, if this is in 
SRAM, then the emmc driver
will init fail, and 'fifo-mode' can work around this issue. So the 
CONFIG_SPL_STACK_R is needed
for emmc/sd controller driver.

Thanks,
- Kever
>
>> It sounds like this should not cause failure if there no one touch the
>> CONFIG_SPL_STACK area.
> I remember while implementing TPL, on vyasa I do take care of this
> STACK_R, so same been reused it for tinker.
>