Re: A133 support

[Parthiban <parthiban@linumiz.com>]

On 10/20/24 4:53 PM, Andre Przywara wrote:
> On Sun, 20 Oct 2024 15:06:46 +0530
> Parthiban <parthiban@linumiz.com> wrote:
> 
> Hi,
> 
>> Am currently adding support for Allwinner A133 SoC based on A100.
> 
> Many thanks for picking this up, but what do you mean exactly by
> "adding support"? As you probably have seen, there is already some

By meaning using the existing compatible and preparing devicetree for
[1].

> basic support for the A100 in the tree, and since we assume that both
> SoCs are basically identical, there wouldn't be too much left to do,
> would there?
> For reference, there is some leftover patch series from the original
> A100 upstreaming attempt, which you could rebase and rework:
> https://lore.kernel.org/linux-arm-kernel/cover.1604988979.git.frank@allwinnertech.com/

Yeah, I did pull few things which were dangling in the series.

> 
> I haven't checked in a while, but some patches in there have either
> been merged or are superseded by other patches, and I guess the others
> need at least a rebase, but it's certainly something worthwhile to work
> on.
> 
>> Based on the [1],
>> A100 and A133 uses same IP across. But there is no public available datasheet or
>> user manual for A100.
> 
> Indeed there has never been, and back then we relied on information
> provided by those Allwinner employees sending the patches.
> For now we assume that the A133 manual describes the A100 as well.
> 
>> Should A100 kept as base and A133 dtsi needs to added on top or A133 can be duplicated
>> into a new devicetree?
> 
> As far as we know, the A133 is the better bin of the A100, so they
> should be identical from the software perspective. This seems to be
> similar to the H616/H313 situation. At some point the A100 totally
> disappeared from Allwinner's documentation (in an almost "Orwellian
> 1984 fashion"), and they only mention the A133 ever since.
> 
> So, since the A100 is already in, and was the first one, I'd say:
> - Keep using an allwinner,sun50i-a100 prefix for any compatible string.
>   Rationale: it's the base model, and was the first one, and we have
>   compatible strings with that in, so we should keep using that for
>   consistency.
> - There is no need for any kind of a133.dtsi, since they are probably
>   identical.
> - If you add a board with an A133, use that name in the root compatible
>   string, but include the a100.dtsi. See the H616/H313/H618 situation,
>   for instance as in sun50i-h618-transpeed-8k618-t.dts.

Thanks for the details. That helps.

> 
> Hope that helps, and thanks for your efforts on improving support for
> that chip! Please come back to the #linux-sunxi IRC channel on OFTC,
> there is someone (MasterR3C0RD) actively working on some A133 board as
> well, and he even has a working DRAM driver for U-Boot. So you should
> coordinate any upstreaming efforts.

Great, am still stuck with 2018 tree from vendor, this will help.

[1]: https://szbaijie.com/index/product/product_detail.html?product_id=23&language=en

Thanks,
Parthiban N
> 
> Cheers
> Andre
> 
> 
> 
> 
>>
>> [1]: https://linux-sunxi.org/Linux_mainlining_effort#Status_Matrix
>>
> 
>