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Date:   Wed, 15 Jul 2020 14:51:20 -0600
From:   Rob Herring <robh@kernel.org>
To:     Miles Chen <miles.chen@mediatek.com>
Cc:     Joerg Roedel <joro@8bytes.org>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        iommu@lists.linux-foundation.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-mediatek@lists.infradead.org, wsd_upstream@mediatek.com,
        Yong Wu <yong.wu@mediatek.com>,
        Chao Hao <chao.hao@mediatek.com>,
        Yingjoe Chen <yingjoe.chen@mediatek.com>
Subject: Re: [PATCH 1/4] dt-bindings: mediatek: add mediatek,infracfg phandle
Message-ID: <20200715205120.GA778876@bogus>
References: <20200702093721.6063-1-miles.chen@mediatek.com>
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On Thu, Jul 02, 2020 at 05:37:17PM +0800, Miles Chen wrote:
> Add a description for mediatek,infracfg. We can check if 4GB mode
> is enable by reading it instead of checking the unexported
> symbol "max_pfn".
> 
> This is a step towards building mtk_iommu as a kernel module.

You determined this before without DT, so it is an OS problem and 
shouldn't need a DT update.

I'd assume there's only one instance of the node mediatek,infracfg 
points to, so just search for it if you want to get the info from DT.


> 
> Cc: Yong Wu <yong.wu@mediatek.com>
> Signed-off-by: Miles Chen <miles.chen@mediatek.com>
> ---
>  Documentation/devicetree/bindings/iommu/mediatek,iommu.txt | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/iommu/mediatek,iommu.txt b/Documentation/devicetree/bindings/iommu/mediatek,iommu.txt
> index ce59a505f5a4..a7881deabcca 100644
> --- a/Documentation/devicetree/bindings/iommu/mediatek,iommu.txt
> +++ b/Documentation/devicetree/bindings/iommu/mediatek,iommu.txt
> @@ -74,6 +74,8 @@ Required properties:
>  - mediatek,larbs : List of phandle to the local arbiters in the current Socs.
>  	Refer to bindings/memory-controllers/mediatek,smi-larb.txt. It must sort
>  	according to the local arbiter index, like larb0, larb1, larb2...
> +- mediatek,infracfg: a phandle to infracfg. It is used to confirm if 4GB mode is set.
> +	It is an optional property, add it when the SoC have 4g mode.
>  - iommu-cells : must be 1. This is the mtk_m4u_id according to the HW.
>  	Specifies the mtk_m4u_id as defined in
>  	dt-binding/memory/mt2701-larb-port.h for mt2701, mt7623
> -- 
> 2.18.0