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

[Ilias Apalodimas]

On Wed, 1 Apr 2026 at 01:01, Marek Vasut <marek.vasut at mailbox.org> wrote:
>
> On 3/31/26 10:01 AM, Ilias Apalodimas wrote:
> > We previously added a fdtdec_setup_mem_ram_top() to determine the
> > topmost address of the last DRAM bank. Similarly the overall memory
> > size must be calculated when U-Boot gets relocated to the actual end of
> > all available DRAM.
> >
> > Pre-patch:
> > U-Boot 2026.04-rc5-00012-g5789f787c8a6-dirty (Mar 31 2026 - 09:13:34 +0300)
> > DRAM:  4 GiB (total 8 GiB)
> >
> > Post-patch:
> > U-Boot 2026.04-rc5-00012-g5789f787c8a6 (Mar 31 2026 - 09:12:59 +0300)
> > DRAM:  8 GiB
> >
> > Signed-off-by: Ilias Apalodimas <ilias.apalodimas at linaro.org>
> > ---
> >   include/fdtdec.h | 15 +++++++++++++++
> >   lib/fdtdec.c     | 18 ++++++++++++++++++
> >   2 files changed, 33 insertions(+)
> >
> > diff --git a/include/fdtdec.h b/include/fdtdec.h
> > index 26e40c3cdb46..9bccd70bbdb6 100644
> > --- a/include/fdtdec.h
> > +++ 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

Thanks
/Ilias