[PATCH] rpi: always set fdt_addr with firmware-provided FDT address

[Matthias Brugger]

Hi Mauro,

On 07/06/2021 11:27, Mauro Salvini wrote:
> On 12/05/21 14:39, Mauro Salvini wrote:
>> Raspberry firmware prepares the FDT blob in memory at an address
>> that depends on both the memory size and the blob size [1].
>> After commit ade243a211d6 ("rpi: passthrough of the firmware provided FDT
>> blob") this FDT is passed to kernel through fdt_addr environment variable,
>> handled in set_fdt_addr() function in board file.
>>
>> When u-boot environment is persistently saved, if a change happens
>> in loaded FDT (e.g. for a new overlay applied), firmware produces a FDT
>> address different from the saved one, but u-boot still use the saved
>> one because set_fdt_addr() function does not overwrite the fdt_addr
>> variable. So, for example, if there is a script that uses fdt commands for
>> e.g. manipulate the bootargs, boot hangs with error
>>
>> libfdt fdt_check_header(): FDT_ERR_BADMAGIC
>>
>> Removing the fdt_addr variable in saved environment allows to boot.
>>
>> With this patch set_fdt_addr() function always overwrite fdt_addr value.
>>
>> [1] https://www.raspberrypi.org/forums//viewtopic.php?f=107&t=134018
>>

First of all sorry for the very late reply.
I'm hesitant to apply this patch, basically because it can break other setups 
where people load a custom DTB to fdt_addr.

I wonder why you can't erase fdt_addr from your persistent storage. There is a 
command called eraseenv that should to the job.

Regards,
Matthias

>> Signed-off-by: Mauro Salvini <m.salvini at koansoftware.com>
>> Cc: Cédric Schieli <cschieli at gmail.com>
>> Cc: Matthias Brugger <mbrugger at suse.com>
>> ---
>>   board/raspberrypi/rpi/rpi.c | 3 ---
>>   1 file changed, 3 deletions(-)
>>
>> diff --git a/board/raspberrypi/rpi/rpi.c b/board/raspberrypi/rpi/rpi.c
>> index df52a4689f..611013471e 100644
>> --- a/board/raspberrypi/rpi/rpi.c
>> +++ b/board/raspberrypi/rpi/rpi.c
>> @@ -318,9 +318,6 @@ static void set_fdtfile(void)
>>    */
>>   static void set_fdt_addr(void)
>>   {
>> -    if (env_get("fdt_addr"))
>> -        return;
>> -
>>       if (fdt_magic(fw_dtb_pointer) != FDT_MAGIC)
>>           return;
>>
> 
> 
> Hi all,
> 
> kind ping.
> 
> Regards
>