[U-Boot] [PATCH 1/4] Revert "sunxi: Move the SPL stack top to 0x1A000 on Allwinner A64/A80"

[Siarhei Siamashka]

On Mon,  5 Sep 2016 01:32:38 +0100
Andre Przywara <andre.przywara at arm.com> wrote:

> This commit moved the SPL stack into SRAM C, which worked when the SPL
> set the AHB1 clock down to 100 MHz to cope with the flaky SRAM C access
> from the CPU.
> However booting with boot0 (and thus not using SPL at all) we still run
> with a 200 MHz AHB1, so any access to SRAM C is prone to fail.
> Since this commit does _not_ only affect the SPL code, but also the
> U-Boot proper, we fail when booting with boot0.

Yes, it unfortunately affected both the SPL and the U-Boot
proper because currently both CONFIG_SPL_STACK and
CONFIG_SYS_INIT_SP_ADDR defines affect the SPL stack
location and in practice this only works in a predictable
way if they are set to the same value. I have sent a patch
to address this problem (but the fix may be unsafe for
v2016.09 because many ARM platforms are affected):

    https://patchwork.ozlabs.org/patch/665608/

After this problem is resolved, the CONFIG_SYS_INIT_SP_ADDR
define can be decoupled from CONFIG_SPL_STACK and configured to
even use the DRAM instead of thrashing some part of the scarce
SRAM space (which may be already occupied by the OpenRISC
firmware and/or the ATF at the time when the U-Boot proper is
starting).

> As the introduction of tiny-printf reduced the size of the SPL, we
> can afford to have the SPL stack in SRAM A1.

We still need to check how much space is really available. The FIT
support is rather heavyweight and we may want to enable some other
features too.
 
> This reverts commit 1a83fb4a17d959d7b037999ab7ed7e62429abe34
> and fixes booting the Pine64 when using boot0.
>
> Signed-off-by: Andre Przywara <andre.przywara at arm.com>

But as discussed earlier, reverting this patch is a reasonable
solution for v2016.09, so it is

Reviewed-by: Siarhei Siamashka <siarhei.siamashka at gmail.com>

> ---
>  include/configs/sunxi-common.h | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/include/configs/sunxi-common.h b/include/configs/sunxi-common.h
> index f64edd4..708ab17 100644
> --- a/include/configs/sunxi-common.h
> +++ b/include/configs/sunxi-common.h
> @@ -99,7 +99,7 @@
>   * the 1 actually activates the mapping of the first 32 KiB to 0x00000000.
>   */
>  #define CONFIG_SYS_INIT_RAM_ADDR	0x10000
> -#define CONFIG_SYS_INIT_RAM_SIZE	0xA000	/* 40 KiB */
> +#define CONFIG_SYS_INIT_RAM_SIZE	0x08000	/* FIXME: 40 KiB ? */
>  #else
>  #define CONFIG_SYS_INIT_RAM_ADDR	0x0
>  #define CONFIG_SYS_INIT_RAM_SIZE	0x8000	/* 32 KiB */
> @@ -220,7 +220,8 @@
>  #define CONFIG_SPL_PAD_TO		32768		/* decimal for 'dd' */
>  
>  #if defined(CONFIG_MACH_SUN9I) || defined(CONFIG_MACH_SUN50I)
> -#define LOW_LEVEL_SRAM_STACK		0x0001A000
> +/* FIXME: 40 KiB instead of 32 KiB ? */
> +#define LOW_LEVEL_SRAM_STACK		0x00018000
>  #define CONFIG_SPL_STACK		LOW_LEVEL_SRAM_STACK
>  #else
>  /* end of 32 KiB in sram */



-- 
Best regards,
Siarhei Siamashka