linux-kernel - Re: [PATCH 11/13] dtb: amd: Add PCIe SMMU device tree node

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Date:	Thu, 28 Jan 2016 11:14:53 +0000
From:	Mark Rutland <mark.rutland@....com>
To:	Suravee Suthikulpanit <Suravee.Suthikulpanit@....com>,
	will.deacon@....com, robin.murphy@....com
Cc:	robh+dt@...nel.org, pawel.moll@....com,
	ijc+devicetree@...lion.org.uk, galak@...eaurora.org, arnd@...db.de,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, arm@...nel.org,
	brijeshkumar.singh@....com, thomas.lendacky@....com,
	leo.duran@....com
Subject: Re: [PATCH 11/13] dtb: amd: Add PCIe SMMU device tree node

On Wed, Jan 27, 2016 at 03:11:59PM -0600, Suravee Suthikulpanit wrote:
> From: Suravee Suthikulpanit <suravee.suthikulpanit@....com>
> 
> Add PCIe SMMU device tree node for AMD Seattle SOC.
> 
> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@....com>
> ---
>  arch/arm64/boot/dts/amd/amd-seattle-soc.dtsi | 23 +++++++++++++++++++++++
>  1 file changed, 23 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/amd/amd-seattle-soc.dtsi b/arch/arm64/boot/dts/amd/amd-seattle-soc.dtsi
> index a7fc059..bfccfea 100644
> --- a/arch/arm64/boot/dts/amd/amd-seattle-soc.dtsi
> +++ b/arch/arm64/boot/dts/amd/amd-seattle-soc.dtsi
> @@ -210,6 +210,7 @@
>  			device_type = "pci";
>  			bus-range = <0 0x7f>;
>  			msi-parent = <&v2m0>;
> +			#stream-id-cells = <16>;
>  			reg = <0 0xf0000000 0 0x10000000>;
>  
>  			interrupt-map-mask = <0xf800 0x0 0x0 0x7>;
> @@ -230,6 +231,28 @@
>  				<0x03000000 0x01 0x00000000 0x01 0x00000000 0x7f 0x00000000>;
>  		};
>  
> +		pcie0_smmu: smmu@...00000 {
> +			 compatible = "arm,mmu-401";
> +			 reg = <0 0xe0a00000 0 0x10000>;
> +			 #global-interrupts = <1>;
> +			 interrupts = /* Uses combined intr for both
> +				       * global and context
> +				       */
> +				      <0 333 4>,
> +				      <0 333 4>;
> +			/* Note:
> +			 * SID[2:0]  = PCIe function number
> +			 * SID[7:3]  = PCIe device number
> +			 * SID[14:8] = PCIe bus number
> +			 */
> +			 mmu-masters = <&pcie0
> +				/* 1:00:[0,3] */ 256 257 258 259
> +				/* 2:00:[0,3] */ 512 513 514 515
> +				/* 3:00:[0,3] */ 768 769 770 771
> +				/* 4:00:[0,3] */ 1024 1025 1026 1027
> +			 >;
> +		 };

This doesn't look right to me.

I didn't think that RID->SID mapping was actually defined by any
binding, so (how) are these numbers used?

I'm uncomfortable with this, given we should be moving towards the
generic IOMMU binding (and then we'd use the iommu-map binding [1] for
this).

Will, Robin, thoughts?

Mark.

[1] https://lkml.org/lkml/2015/7/23/561