[U-Boot] [PATCH 3/3] arm: socfpga: put initial U-Boot stack into DDR

[Simon Goldschmidt]

On Thu, Feb 28, 2019 at 10:44 PM Marek Vasut <marex at denx.de> wrote:
>
> On 2/28/19 9:33 PM, Simon Goldschmidt wrote:
> > If SPL pre-reloc stage puts the stack into DDR, U-Boot should be able to
> > do that, too.
>
> Here you mention SPL pre-reloc stage, while about mid-way through the
> patch you have a comment talking about SPL post-reloc stage, which one
> is it ? I think the commit message needs rewording, it's not clear what
> the patch does based on it.

Ehrm right. The commit message is wrong. Post-reloc is correct.

> On a separate note, this is likely a fix for current release, right ?

Not really. For A10, this should not change anything, just ensure the common
header file does not use 2 different ways to achieve the same thing.
Note that A10 does *not* enable a different stack/malloc area for SPL
post-reloc!

For gen5, yes there is a change, but only in U-Boot, not in SPL. But this is
not a fix, it's an improvement to be able to make the SPL malloc pool smaller
without U-Boot overwriting it. It's currently not overwritten as both
malloc sizes
are the same. I'd change that in a follow-up patch which reduces SPL malloc
size for gen5.

> Finally , keep in mind the A10 needs to load the FPGA before DRAM
> becomes available, so the stack shenanigans there become even more nasty.

Right, that's why even the initial malloc size for SPL is 64 KiB,
right? As written
above, this patch should not change anything for A10, so this should still work.

>From reading the A10 SPL code, I didn't quite get how this works though, as
it seems the simple-malloc members in gd are only initialized after
spl_early_init(), so after initializing DT/DM? Or is A10 not yet
converted to DT?

Regards,
Simon

> > The reason to do so is that this way, U-Boot initial stack can be larger
> > than SPL initial stack. In situations where we want to save the SPL
> > in SRAM for next boot without reloading, this prevents overwriting the
> > SPL DTB in SRAM if U-Boot stack usage gets too high.
> >
> > Signed-off-by: Simon Goldschmidt <simon.k.r.goldschmidt at gmail.com>
> > ---
> >
> >  include/configs/socfpga_common.h | 20 +++++++++++++-------
> >  1 file changed, 13 insertions(+), 7 deletions(-)
> >
> > diff --git a/include/configs/socfpga_common.h b/include/configs/socfpga_common.h
> > index c23b34186a..7ae3db233f 100644
> > --- a/include/configs/socfpga_common.h
> > +++ b/include/configs/socfpga_common.h
> > @@ -38,12 +38,23 @@
> >  #if ((CONFIG_SYS_BOOTCOUNT_ADDR > CONFIG_SYS_INIT_RAM_ADDR) &&       \
> >       (CONFIG_SYS_BOOTCOUNT_ADDR < (CONFIG_SYS_INIT_RAM_ADDR +        \
> >                                  CONFIG_SYS_INIT_RAM_SIZE)))
> > -#define CONFIG_SYS_INIT_SP_ADDR              CONFIG_SYS_BOOTCOUNT_ADDR
> > +#define CONFIG_SPL_STACK             CONFIG_SYS_BOOTCOUNT_ADDR
> >  #else
> > -#define CONFIG_SYS_INIT_SP_ADDR                      \
> > +#define CONFIG_SPL_STACK                     \
> >       (CONFIG_SYS_INIT_RAM_ADDR + CONFIG_SYS_INIT_RAM_SIZE)
> >  #endif
> >
> > +/*
> > + * U-Boot stack setup: if SPL post-reloc uses DDR stack, use it in pre-reloc
> > + * phase of U-Boot, too. This prevents overwriting SPL data if stack/heap usage
> > + * in U-Boot pre-reloc is higher than in SPL.
> > + */
> > +#if defined(CONFIG_SPL_STACK_R_ADDR) && CONFIG_SPL_STACK_R_ADDR
> > +#define CONFIG_SYS_INIT_SP_ADDR              CONFIG_SPL_STACK_R_ADDR
> > +#else
> > +#define CONFIG_SYS_INIT_SP_ADDR              CONFIG_SPL_STACK
> > +#endif
> > +
> >  #define CONFIG_SYS_SDRAM_BASE                PHYS_SDRAM_1
> >
> >  /*
> > @@ -274,11 +285,6 @@ unsigned int cm_get_qspi_controller_clk_hz(void);
> >  #define CONFIG_SYS_NAND_U_BOOT_OFFS  0x40000
> >  #endif
> >
> > -/*
> > - * Stack setup
> > - */
> > -#define CONFIG_SPL_STACK             CONFIG_SYS_INIT_SP_ADDR
> > -
> >  /* Extra Environment */
> >  #ifndef CONFIG_SPL_BUILD
> >
> >
>
>
> --
> Best regards,
> Marek Vasut