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Date:   Thu, 4 Nov 2021 12:02:37 -0700 (PDT)
From:   Stefano Stabellini <sstabellini@kernel.org>
To:     David Heidelberg <david@ixit.cz>
cc:     Tom Lendacky <thomas.lendacky@amd.com>,
        Brijesh Singh <brijeshkumar.singh@amd.com>,
        Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>,
        Rob Herring <robh+dt@kernel.org>,
        Andy Gross <agross@kernel.org>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        Michal Simek <michal.simek@xilinx.com>,
        ~okias/devicetree@lists.sr.ht, netdev@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-msm@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, sstabellini@kernel.org
Subject: Re: [PATCH] arm64: dts: drop legacy property #stream-id-cells
In-Reply-To: <20211030103117.33264-1-david@ixit.cz>
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References: <20211030103117.33264-1-david@ixit.cz>
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On Sat, 30 Oct 2021, David Heidelberg wrote:
> Property #stream-id-cells is legacy leftover and isn't currently
> documented nor used.
> 
> Signed-off-by: David Heidelberg <david@ixit.cz>
> ---
>  .../boot/dts/amd/amd-seattle-xgbe-b.dtsi      |  2 --
>  arch/arm64/boot/dts/qcom/msm8996.dtsi         |  1 -
>  arch/arm64/boot/dts/qcom/msm8998.dtsi         |  1 -
>  arch/arm64/boot/dts/qcom/sc7180.dtsi          |  1 -
>  arch/arm64/boot/dts/qcom/sc7280.dtsi          |  1 -
>  arch/arm64/boot/dts/qcom/sdm630.dtsi          |  1 -
>  arch/arm64/boot/dts/qcom/sdm845.dtsi          |  1 -
>  arch/arm64/boot/dts/qcom/sm8150.dtsi          |  1 -
>  arch/arm64/boot/dts/qcom/sm8250.dtsi          |  1 -
>  arch/arm64/boot/dts/xilinx/zynqmp.dtsi        | 28 -------------------
>  10 files changed, 38 deletions(-)
> 
> diff --git a/arch/arm64/boot/dts/amd/amd-seattle-xgbe-b.dtsi b/arch/arm64/boot/dts/amd/amd-seattle-xgbe-b.dtsi
> index d97498361ce3..3e9faace47f2 100644
> --- a/arch/arm64/boot/dts/amd/amd-seattle-xgbe-b.dtsi
> +++ b/arch/arm64/boot/dts/amd/amd-seattle-xgbe-b.dtsi
> @@ -55,7 +55,6 @@ xgmac0: xgmac@e0700000 {
>  		clocks = <&xgmacclk0_dma_250mhz>, <&xgmacclk0_ptp_250mhz>;
>  		clock-names = "dma_clk", "ptp_clk";
>  		phy-mode = "xgmii";
> -		#stream-id-cells = <16>;
>  		dma-coherent;
>  	};
>  
> @@ -81,7 +80,6 @@ xgmac1: xgmac@e0900000 {
>  		clocks = <&xgmacclk1_dma_250mhz>, <&xgmacclk1_ptp_250mhz>;
>  		clock-names = "dma_clk", "ptp_clk";
>  		phy-mode = "xgmii";
> -		#stream-id-cells = <16>;
>  		dma-coherent;
>  	};

#stream-id-cells is used to parse the legacy mmu-masters property (which
by the way Xen is still capable of parsing [1]).

So #stream-id-cells should be present if mmu-masters is present.

Looking at the patch and grepping for mmu-masters,
amd-seattle-xgbe-b.dtsi is the only one that has mmu-masters. So I think
this change to amd-seattle-xgbe-b.dtsi should be removed from the patch.
Everything else is fine.


[1] https://gitlab.com/xen-project/xen/-/blob/staging/xen/drivers/passthrough/arm/smmu.c#L2477