linux-kernel - Re: [PATCH v2] soc: mediatek: Add deprecated compatible to mmsys

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Date:   Fri, 16 Dec 2022 14:33:33 +0100
From:   Matthias Brugger <matthias.bgg@...il.com>
To:     Chen-Yu Tsai <wenst@...omium.org>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>, matthias.bgg@...nel.org
Cc:     nancy.lin@...iatek.com, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] soc: mediatek: Add deprecated compatible to mmsys



On 01/12/2022 12:20, Chen-Yu Tsai wrote:
> On Mon, Nov 14, 2022 at 7:59 PM AngeloGioacchino Del Regno
> <angelogioacchino.delregno@...labora.com> wrote:
>>
>> Il 11/11/22 09:29, matthias.bgg@...nel.org ha scritto:
>>> From: Matthias Brugger <matthias.bgg@...il.com>
>>>
>>> For backward compatibility we add the deprecated compatible.
>>>
>>> Signed-off-by: Matthias Brugger <matthias.bgg@...il.com>
>>
>> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
>>
>> ...And tested on MT8195 Cherry Chromebook.
> 
> This now seems like a bad idea. In the dtsi we have two nodes (vdosys0 and
> vdosys1) that both currently use the -mmsys compatible, which in the driver
> maps to vdosys0. So not only do we have vdosys1 incorrectly probing as
> vdosys0, we also have duplicate clks being registered and duplicate DRM
> pipelines. On my device vdosys1 ends up winning the duplicate clock race.
> 

That's true, we should fix the DTS deleting vdosys1 node as it's not 
implemented. While at it we should also fix the compatible for vdosys0 as 
"mediatek,mt8195-mmsys" is now deprecated.

Would you mind to send a patch?

Regards,
Matthias

> I suggest just reverting this. The display stuff won't be useful unless
> the drivers are able to distinguish themselves from one another.
>