[PATCH][RFC] image: fdt: Fix DT relocation handling with multiple DRAM banks with gap

[Marek Vasut]

On 3/12/22 03:24, Simon Glass wrote:
> Hi Marek,
> 
> On Wed, 21 Jul 2021 at 18:05, Marek Vasut <marex at denx.de> wrote:
>>
>> The current implementation of boot_relocate_fdt() places DT at the
>> highest usable DRAM address, which is calculated as:
>>    env_get_bootm_low() + env_get_bootm_mapsize()
>> which by default becomes gd->ram_base + gd->ram_size.
>>
>> Systems like i.MX53 can have multiple DRAM banks with gap between them,
>> e.g. have DRAM at 0x70000000-0x8fffffff and 0xb0000000-0xcfffffff , so
>> for them the calculated highest DRAM address is 0xafffffff, which is
>> exactly in the gap and thus not usable.
>>
>> Fix this by iterating over all DRAM banks and tracking the remaining
>> amount of the total mapping size obtained from env_get_bootm_mapsize().
>> Limit the maximum LMB area size to each bank, to avoid using nonexistent
>> DRAM.
>>
>> Signed-off-by: Marek Vasut <marex at denx.de>
>> Cc: Heinrich Schuchardt <xypron.glpk at gmx.de>
>> Cc: Simon Glass <sjg at chromium.org>
>> Cc: Tom Rini <trini at konsulko.com>
>> ---
>>   common/image-fdt.c | 40 ++++++++++++++++++++++++++++++++++++----
>>   1 file changed, 36 insertions(+), 4 deletions(-)
> 
> Reviewed-by: Simon Glass <sjg at chromium.org>
> 
> Should we put this behind a Kconfig option to reduce code size?

Since this depends on DT content, we cannot predict what kind of DT will 
be passed to U-Boot, so no, we cannot put this behind a Kconfig option.