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

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Message-ID: <CAGXv+5FORS=iGe55StxR_1E3sdtk9cvitfvNa1SydqCjWGcubg@mail.gmail.com>
Date:   Thu, 1 Dec 2022 19:20:14 +0800
From:   Chen-Yu Tsai <wenst@...omium.org>
To:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>, matthias.bgg@...nel.org
Cc:     matthias.bgg@...il.com, 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 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.

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

Regards
ChenYu