[PATCH v1 2/3] fdtdec: Introduce fdtdec_setup_mem_ram_top() to determine end of topmost DRAM bank

[Marek Vasut]

On 3/27/26 1:19 PM, Ilias Apalodimas wrote:

Hello Ilias,

> On Thu, 26 Mar 2026 at 22:40, Marek Vasut <marek.vasut at mailbox.org> wrote:
>>
>> On 3/26/26 12:51 PM, Ilias Apalodimas wrote:
>>
>> [...]
>>
>>> +/**
>>> + * fdtdec_setup_mem_ram_top() - decode and setup gd->ram_top to highest address
>>> + * available in any memory bank
>>> + *
>>> + * Decode the /memory 'reg' property to determine the highest end of the memory
>>> + * bank and populate the global data ram_top with it.
>>> + *
>>> + * This function should be called from a boards board_get_usable_ram_top().
>>> + * This helper function allows for boards to query the device tree for topmost
>>> + * DRAM address.
>>> + *
>>> + * Return: 0 if OK, -EINVAL if the /memory node or reg property is missing or
>>> + * invalid
>>> + */
>>> +int fdtdec_setup_mem_ram_top(void);
>>> +
>>>    /**
>>>     * fdtdec_setup_memory_banksize() - decode and populate gd->bd->bi_dram
>>>     *
>>> diff --git a/lib/fdtdec.c b/lib/fdtdec.c
>>> index d820f75b031d..c5ee2ecb3a49 100644
>>> --- a/lib/fdtdec.c
>>> +++ b/lib/fdtdec.c
>>> @@ -1162,6 +1162,26 @@ int fdtdec_setup_mem_size_base_lowest(void)
>>>        return fdtdec_setup_mem_for_each_bank(fdtdec_setup_mem_size_base_lowest_bankfn);
>>>    }
>>>
>>> +static void fdtdec_setup_mem_ram_top_bankfn(struct resource *res, int bank)
>>> +{
>>> +     if ((res->end + 1) > gd->ram_top) {
>>> +             gd->ram_top = res->end + 1;
>>> +             gd->ram_size += res->end - res->start;
>> Since this is called fdtdec_setup_mem_ram_top(), it likely shouldn't be
>> manipulating with gd->ram_size ?
> 
> Sure. I don;t mind either way. We either rename the function to
> something more readable or just add a new callback that updates the
> sizes.
> I'll just move this to a new callback.
Thank you