[PATCH v2 3/4] fdtdec: Introduce fdtdec_setup_ram_size() to determine the memory size

[Ilias Apalodimas]

Hi Marek,

On Wed, 1 Apr 2026 at 18:24, Marek Vasut <marek.vasut at mailbox.org> wrote:
>
> On 4/1/26 8:43 AM, Ilias Apalodimas wrote:
>
> >>> +++ b/include/fdtdec.h
> >>> @@ -965,6 +965,21 @@ int fdtdec_setup_mem_ram_top(void);
> >>>     * invalid
> >>>     */
> >>>    int fdtdec_setup_memory_banksize(void);
> >>> +/**
> >>> + * fdtdec_setup_ram_size() - decode and setup setup gd->ram_size to the sum of
> >>> + *                        all banks
> >>> + *
> >>> + * Decode the /memory 'reg' property to determine the memory available in all
> >>> + * banks and populate the global data ram_size with it.
> >>> + *
> >>> + * This function should be called from a boards board_get_usable_ram_top().
> >>
> >> Is the board_get_usable_ram_top() really the right place to call this ?
> >> It feels like it is being conflated with ram_top here too.
> >
> > I don't think so. You are effectively calculating the top address you
> > should relocate to. You should also calculate the difference in
> > ramsize. Those two should not be separated actions
> The address where you relocate to is gd->relocaddr, which is ram_top
> minus all the reserved areas, see common/board_f.c setup_dest_addr().
>
> This setup_dest_addr() function does manipulate with gd->ram_size , but
> only to handle CONFIG_SYS_MEM_TOP_HIDE , which may not be the right
> place for it, I think it would be better to have a separate initcall for
> the ram_size calculation, which precedes setup_dest_addr().

Yes, but when you calculate the reloc address and use a bigger
ram_top, the right thing to do is adjust the size as well

>
> With that, the function description can claim that each function must be
> called before that specific initcall, fdtdec_setup_mem_ram_top() before
> setup_dest_addr() and fdtdec_setup_ram_size() before
> setup_whatever_is_the_new_initcall_name().

I really don't mind. I just don't see the point of making things so
granular. Unless I am wrong and someone thinks it makes sense to
change ram_top without taking into account the size.

Thanks
/Ilias