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Date:   Tue, 21 Sep 2021 15:36:42 -0500
From:   Rob Herring <robh@kernel.org>
To:     Yong Wu <yong.wu@mediatek.com>
Cc:     Ikjoon Jang <ikjn@chromium.org>,
        Krzysztof Kozlowski <krzk@kernel.org>, youlin.pei@mediatek.com,
        Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>,
        devicetree@vger.kernel.org, Joerg Roedel <joro@8bytes.org>,
        linux-kernel@vger.kernel.org, yi.kuo@mediatek.com,
        anan.sun@mediatek.com, Tomasz Figa <tfiga@chromium.org>,
        ming-fan.chen@mediatek.com,
        Matthias Brugger <matthias.bgg@gmail.com>,
        linux-arm-kernel@lists.infradead.org,
        Will Deacon <will@kernel.org>, srv_heupstream@mediatek.com,
        linux-mediatek@lists.infradead.org,
        iommu@lists.linux-foundation.org, Rob Herring <robh+dt@kernel.org>,
        anthony.huang@mediatek.com, Robin Murphy <robin.murphy@arm.com>
Subject: Re: [PATCH v4 02/13] dt-bindings: memory: mediatek: Add mt8195 smi
 sub common
Message-ID: <YUpCWib8Tpf0wfif@robh.at.kernel.org>
References: <20210914113703.31466-1-yong.wu@mediatek.com>
 <20210914113703.31466-3-yong.wu@mediatek.com>
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On Tue, 14 Sep 2021 19:36:52 +0800, Yong Wu wrote:
> Add the binding for smi-sub-common. The SMI block diagram like this:
> 
>         IOMMU
>          |  |
>       smi-common
>   ------------------
>   |      ....      |
>  larb0           larb7   <-max is 8
> 
> The smi-common connects with smi-larb and IOMMU. The maximum larbs number
> that connects with a smi-common is 8. If the engines number is over 8,
> sometimes we use a smi-sub-common which is nearly same with smi-common.
> It supports up to 8 input and 1 output(smi-common has 2 output)
> 
> Something like:
> 
>         IOMMU
>          |  |
>       smi-common
>   ---------------------
>   |      |          ...
> larb0  sub-common   ...   <-max is 8
>       -----------
>        |    |    ...   <-max is 8 too.
>      larb2 larb5
> 
> We don't need extra SW setting for smi-sub-common, only the sub-common has
> special clocks need to enable when the engines access dram.
> 
> If it is sub-common, it should have a "mediatek,smi" phandle to point to
> its smi-common. meanwhile the sub-common only has one gals clock.
> 
> Signed-off-by: Yong Wu <yong.wu@mediatek.com>
> ---
> change note: add "else mediatek,smi: false".
> ---
>  .../mediatek,smi-common.yaml                  | 28 +++++++++++++++++++
>  1 file changed, 28 insertions(+)
> 

Reviewed-by: Rob Herring <robh@kernel.org>