Re: [PATCH v3 1/2] arm64: dts: mediatek: mt8195-demo: fix the memory size to 8GB

[Macpaul Lin <macpaul.lin@mediatek.com>]

On 9/5/23 16:00, AngeloGioacchino Del Regno wrote:
> Il 05/09/23 05:45, Macpaul Lin ha scritto:
>> The onboard dram of mt8195-demo board is 8GB.
>>
>> Cc: stable@vger.kernel.org      # 6.1, 6.4, 6.5
>> Fixes: 6147314aeedc ("arm64: dts: mediatek: Add device-tree for MT8195 
>> Demo board")
>> Signed-off-by: Macpaul Lin <macpaul.lin@mediatek.com>
>> ---
>>   arch/arm64/boot/dts/mediatek/mt8195-demo.dts | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> Changes for v2:
>> Changes for v3:
>>   - No change.
>>
>> diff --git a/arch/arm64/boot/dts/mediatek/mt8195-demo.dts 
>> b/arch/arm64/boot/dts/mediatek/mt8195-demo.dts
>> index b2485ddfd33b..ff363ab925e9 100644
>> --- a/arch/arm64/boot/dts/mediatek/mt8195-demo.dts
>> +++ b/arch/arm64/boot/dts/mediatek/mt8195-demo.dts
>> @@ -48,7 +48,7 @@
>>       memory@40000000 {
>>           device_type = "memory";
>> -        reg = <0 0x40000000 0 0x80000000>;
>> +        reg = <0 0x40000000 0x2 0x00000000>;
> 
> Shouldn't this get automatically filled in by the bootloader?
> Usually, that's the case: if it is, then the right thing to do here
> is to change this property to
> 
>          /* The bootloader will fill in the size */
>          reg = <0x0 0x40000000 0x0 0x0>;
> 
> Regards,
> Angelo
> 

Thanks for the review. However, this value seems depends on the boot 
method. Take u-boot as the example, the total memory size which Linux 
kernel get will be different via EBBR boot or fitImage boot.

It the system is booted through EBBR, the memory size should be filled 
by u-boot's UEFI variables, which is from u-boot's dts file. If the 
system is booted from fitImage, the memory size should be filled by 
kernel's dts file which is usually packed with fitImage. That's why we 
still need this fix.

>>       };
>>       reserved-memory {
> 
> 

Thanks.
Macpaul Lin