linux-kernel - Re: [PATCH V2 3/3] arm64: dts: nvidia: Add nodes for CMDQV

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Message-ID: <r2mkiktazyn3nvhirbs2ac7n5ymdw62ueutpxt55cnivdi7pdn@6i4hjtvxp2ph>
Date: Mon, 1 Dec 2025 15:11:00 +0100
From: Thierry Reding <thierry.reding@...il.com>
To: Ashish Mhetre <amhetre@...dia.com>
Cc: Jon Hunter <jonathanh@...dia.com>, will@...nel.org, 
	robin.murphy@....com, joro@...tes.org, robh@...nel.org, krzk+dt@...nel.org, 
	conor+dt@...nel.org, nicolinc@...dia.com, vdumpa@...dia.com, jgg@...pe.ca, 
	linux-arm-kernel@...ts.infradead.org, iommu@...ts.linux.dev, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-tegra@...r.kernel.org
Subject: Re: [PATCH V2 3/3] arm64: dts: nvidia: Add nodes for CMDQV

On Mon, Dec 01, 2025 at 03:06:55PM +0530, Ashish Mhetre wrote:
> 
> On 11/25/2025 3:52 PM, Jon Hunter wrote:
> > 
> > 
> > On 25/11/2025 07:16, Ashish Mhetre wrote:
> > > The Command Queue Virtualization (CMDQV) hardware is part of the
> > > SMMUv3 implementation on NVIDIA Tegra SoCs. It assists in
> > > virtualizing the command queue for the SMMU.
> > > 
> > > Update SMMU compatible strings to use nvidia,tegra264-smmu to enable
> > > CMDQV support. Add device tree nodes for the CMDQV hardware and enable
> > > them on the tegra264-p3834 platform where SMMUs are enabled. Each SMMU
> > > instance is paired with its corresponding CMDQV instance via the
> > > nvidia,cmdqv property.
> > > 
> > > Signed-off-by: Ashish Mhetre <amhetre@...dia.com>
> > > ---
> > >   .../arm64/boot/dts/nvidia/tegra264-p3834.dtsi |  8 +++
> > >   arch/arm64/boot/dts/nvidia/tegra264.dtsi      | 55 +++++++++++++++++--
> > >   2 files changed, 58 insertions(+), 5 deletions(-)
> > > 
> > > diff --git a/arch/arm64/boot/dts/nvidia/tegra264-p3834.dtsi
> > > b/arch/arm64/boot/dts/nvidia/tegra264-p3834.dtsi
> > > index 06795c82427a..375d122b92fa 100644
> > > --- a/arch/arm64/boot/dts/nvidia/tegra264-p3834.dtsi
> > > +++ b/arch/arm64/boot/dts/nvidia/tegra264-p3834.dtsi
> > > @@ -26,5 +26,13 @@ iommu@...0000 {
> > >           iommu@...0000 {
> > >               status = "okay";
> > >           };
> > > +
> > > +        cmdqv@...0000 {
> > > +            status = "okay";
> > > +        };
> > 
> > This needs to be ordered in the file according to its address.
> 
> Hi Jon, Thanks for the review.
> cmdqv nodes follow same ordering as its corresponding iommu nodes.
> I have added them immediately after corresponding iommu nodes.

No, you didn't. It seems like you sorted by type and then address. But
we always sort by address first. Type doesn't matter.

This node belongs above the iommu@...0000 node and after iommu@...0000.
The same ordering should be respected in the DTS include.

Thierry

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