linux-kernel - Re: [PATCH 1/3] dt-bindings: mt8173: Fix mdp device tree

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Message-ID: <20170419213540.4vigeed3mx24ie4e@rob-hp-laptop>
Date:   Wed, 19 Apr 2017 16:35:40 -0500
From:   Rob Herring <robh@...nel.org>
To:     Minghsiu Tsai <minghsiu.tsai@...iatek.com>
Cc:     Hans Verkuil <hans.verkuil@...co.com>, daniel.thompson@...aro.org,
        Mauro Carvalho Chehab <mchehab@....samsung.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Daniel Kurtz <djkurtz@...omium.org>,
        Pawel Osciak <posciak@...omium.org>,
        Houlong Wei <houlong.wei@...iatek.com>,
        srv_heupstream@...iatek.com,
        Eddie Huang <eddie.huang@...iatek.com>,
        Yingjoe Chen <yingjoe.chen@...iatek.com>,
        Wu-Cheng Li <wuchengli@...gle.com>, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-media@...r.kernel.org, linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH 1/3] dt-bindings: mt8173: Fix mdp device tree

On Thu, Apr 13, 2017 at 03:33:05PM +0800, Minghsiu Tsai wrote:
> If the mdp_* nodes are under an mdp sub-node, their corresponding
> platform device does not automatically get its iommu assigned properly.
> 
> Fix this by moving the mdp component nodes up a level such that they are
> siblings of mdp and all other SoC subsystems.  This also simplifies the
> device tree.

It may simplify the DT, but it also breaks compatibility with old DT. 
Not sure if that's a problem on Mediatek platforms, but please be 
explicit here that you are breaking compatibility and why that is okay.

> 
> Signed-off-by: Daniel Kurtz <djkurtz@...omium.org>
> Signed-off-by: Minghsiu Tsai <minghsiu.tsai@...iatek.com>

Should this have Daniel as the author?

> 
> ---
>  Documentation/devicetree/bindings/media/mediatek-mdp.txt | 12 +++---------
>  1 file changed, 3 insertions(+), 9 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/media/mediatek-mdp.txt b/Documentation/devicetree/bindings/media/mediatek-mdp.txt
> index 4182063..0d03e3a 100644
> --- a/Documentation/devicetree/bindings/media/mediatek-mdp.txt
> +++ b/Documentation/devicetree/bindings/media/mediatek-mdp.txt
> @@ -2,7 +2,7 @@
>  
>  Media Data Path is used for scaling and color space conversion.
>  
> -Required properties (controller (parent) node):
> +Required properties (controller node):
>  - compatible: "mediatek,mt8173-mdp"
>  - mediatek,vpu: the node of video processor unit, see
>    Documentation/devicetree/bindings/media/mediatek-vpu.txt for details.
> @@ -32,21 +32,16 @@ Required properties (DMA function blocks, child node):
>    for details.
>  
>  Example:
> -mdp {
> -	compatible = "mediatek,mt8173-mdp";
> -	#address-cells = <2>;
> -	#size-cells = <2>;
> -	ranges;
> -	mediatek,vpu = <&vpu>;
> -
>  	mdp_rdma0: rdma@...01000 {
>  		compatible = "mediatek,mt8173-mdp-rdma";
> +			     "mediatek,mt8173-mdp";
>  		reg = <0 0x14001000 0 0x1000>;
>  		clocks = <&mmsys CLK_MM_MDP_RDMA0>,
>  			 <&mmsys CLK_MM_MUTEX_32K>;
>  		power-domains = <&scpsys MT8173_POWER_DOMAIN_MM>;
>  		iommus = <&iommu M4U_PORT_MDP_RDMA0>;
>  		mediatek,larb = <&larb0>;
> +		mediatek,vpu = <&vpu>;
>  	};
>  
>  	mdp_rdma1: rdma@...02000 {
> @@ -106,4 +101,3 @@ mdp {
>  		iommus = <&iommu M4U_PORT_MDP_WROT1>;
>  		mediatek,larb = <&larb4>;
>  	};
> -};
> -- 
> 1.9.1
>