linux-kernel - Re: [PATCH v2 2/5] media: dt-bindings: mediatek,vcodec: Remove VDEC

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Date:   Thu, 8 Jun 2023 17:48:32 +0100
From:   Conor Dooley <conor@...nel.org>
To:     Nícolas F. R. A. Prado 
        <nfraprado@...labora.com>
Cc:     Matthias Brugger <matthias.bgg@...il.com>,
        Hans Verkuil <hverkuil-cisco@...all.nl>, kernel@...labora.com,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        Andrew-CT Chen <andrew-ct.chen@...iatek.com>,
        Conor Dooley <conor+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Tiffany Lin <tiffany.lin@...iatek.com>,
        Yunfei Dong <yunfei.dong@...iatek.com>,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
        linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH v2 2/5] media: dt-bindings: mediatek,vcodec: Remove
 VDEC_SYS for mt8183

On Wed, Jun 07, 2023 at 04:53:39PM -0400, Nícolas F. R. A. Prado wrote:
> The binding expects the first register space to be VDEC_SYS. But on
> mt8183, which uses the stateless decoders, this space is used only for
> controlling clocks and resets, which are better described as separate
> clock-controller and reset-controller nodes.
> 
> In fact, in mt8173's devicetree there are already such separate
> clock-controller nodes, which cause duplicate addresses between the
> vdecsys node and the vcodec node. But for this SoC, since the stateful
> decoder code makes other uses of the VDEC_SYS register space, it's not
> straightforward to remove it.
> 
> In order to avoid the same address conflict to happen on mt8183,
> since the only current use of the VDEC_SYS register space in
> the driver is to read the status of a clock that indicates the hardware
> is active, remove the VDEC_SYS register space from the binding and
> describe an extra clock that will be used to directly check the hardware
> status.
> 
> While adding the active clock, split the mt8183 clocks since there are
> less of them than in mt8173. This is done in this same commit to avoid
> changing the number of clocks twice.
> 
> Also add reg-names to be able to tell that this new register schema is
> used, so the driver can keep backward compatibility.

Rationale here seems to make sense to me & seems like whatever
functionality, or lack thereof, for the mt8183 will be preserved w/ the
old devicetree.
Reviewed-by: Conor Dooley <conor.dooley@...rochip.com>

Cheers,
Conor.

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