Re: [PATCH 2/2] ARM: at91: dts: at91-sama5d2_xplained: Add comments for sama5d29

[<Hari.PrasathGE@microchip.com>]

Hello,

On 13/08/21 12:56 am, Alexandre Belloni wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> Hello,
> 
> On 12/08/2021 19:37:58+0530, Hari Prasath wrote:
>> Add comments for the end user for modifying the DTS file for
>> instantiating the sama5d29 SoC.
>>
>> Signed-off-by: Hari Prasath <Hari.PrasathGE@microchip.com>
>> ---
>>   arch/arm/boot/dts/at91-sama5d2_xplained.dts | 5 +++++
>>   1 file changed, 5 insertions(+)
>>
>> diff --git a/arch/arm/boot/dts/at91-sama5d2_xplained.dts b/arch/arm/boot/dts/at91-sama5d2_xplained.dts
>> index 627b7bf88d83..faa30063d9a9 100644
>> --- a/arch/arm/boot/dts/at91-sama5d2_xplained.dts
>> +++ b/arch/arm/boot/dts/at91-sama5d2_xplained.dts
>> @@ -6,6 +6,11 @@
>>    *                2015 Nicolas Ferre <nicolas.ferre@atmel.com>
>>    */
>>   /dts-v1/;
>> +/*
>> + * Replace the line below with "sama5d29.dtsi" in order to instantiate the
>> + * sama5d29 SoC of the sama5d2 family.Otherwise, leave it unchanged when
>> + * using sama5d27 SoC for instance.
>> + */
> 
> I guess it would be better to have a at91-sama5d29_xplained.dts (and we
> should have had a at91-sama5d27_xplained.dts), else, you can't create an
> image that will support both variants.
> 
> 
The new SoC 'sama5d29' belongs to the same sama5d2 family. It is 
essentially a new chip revision of the existing sama5d27 with a new GMAC 
controller IP that addresses few silicon issues. There wouldn't be 
separate evaluation boards that shall be made but we will be using the 
existing sama5d2 XPlained boards itself but with the new SoC populated. 
Hence we have taken this approach of having a separate DTSI file and 
reuse the existing board specific DTS file.

We don't want to create single image that will support both variants. In 
fact, we don't want our customers to enable certain features that are 
broken at the silicon level in the existing revision of the SoC i.e 
sama5d27. Instead, they could do this change manually and use it in the 
new SoC i.e sama5d29.

Regards,
Hari

> --
> Alexandre Belloni, co-owner and COO, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com
>