[PATCH 2/2] arm: dts: am571x-idk: Reserve EMIF memory used by PPA

[Padhi, Beleswar]

On 11/28/2025 1:44 PM, Kumar, Udit wrote:
>
> On 11/28/2025 12:13 PM, Beleswar Padhi wrote:
>> The AM571x SoC has 1 GB DDR space. However on HS devices, the top
>> 0x2500000 is used by PPA and is firewalled. We should reserve this
>> memory in device-tree so that U-Boot doesn't use that memory for
>> anything. Reserve the top 0x2600000 memory (aligned to 2MB as per page
>> size for ARM32) for the same.
>>
>> Signed-off-by: Beleswar Padhi <b-padhi at ti.com>
>> ---
>>   arch/arm/dts/am571x-idk.dts | 12 ++++++++++++
>>   1 file changed, 12 insertions(+)
>>
>> diff --git a/arch/arm/dts/am571x-idk.dts b/arch/arm/dts/am571x-idk.dts
>> index b3592b22a0c..0cbd8c8a685 100644
>> --- a/arch/arm/dts/am571x-idk.dts
>> +++ b/arch/arm/dts/am571x-idk.dts
>> @@ -20,6 +20,18 @@
>>           reg = <0x0 0x80000000 0x0 0x40000000>;
>>       };
>>   +    reserved-memory {
>> +        #address-cells = <2>;
>> +        #size-cells = <2>;
>> +        ranges;
>> +
>> +        ppa_firewall_memory_region: ppa-firewall-memory at bda00000 {
>> +            compatible = "shared-dma-pool";
>> +            reg = <0x00 0xbda00000 0x00 0x2600000>;
>> +            no-map;
>> +        };
>> +    };
>
> You will lose this memory on GP device as well .
>
> I suggest to have DT specific to HS device, or reserve this at 
> run-time after detecting HS device.


Thanks, while trying to do this via FDT fixups, found out it was already 
taken care of by:

https://github.com/u-boot/u-boot/blob/master/arch/arm/mach-omap2/fdt-common.c#L72-L107


Thanks,
Beleswar