linux-kernel - Re: [PATCH 1/3] iommu/arm-smmu-v3: Add device-tree support for CMDQV driver

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Message-ID: <aQTyBBF0IoE+pcXW@Asurada-Nvidia>
Date: Fri, 31 Oct 2025 10:29:40 -0700
From: Nicolin Chen <nicolinc@...dia.com>
To: Ashish Mhetre <amhetre@...dia.com>
CC: <will@...nel.org>, <robin.murphy@....com>, <joro@...tes.org>,
	<robh@...nel.org>, <krzk+dt@...nel.org>, <conor+dt@...nel.org>,
	<thierry.reding@...il.com>, <jonathanh@...dia.com>, <jgg@...pe.ca>,
	<linux-tegra@...dia.com>, <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 1/3] iommu/arm-smmu-v3: Add device-tree support for CMDQV
 driver

On Fri, Oct 31, 2025 at 06:29:57AM +0000, Ashish Mhetre wrote:
> Add device tree support to the CMDQV driver to enable usage on Tegra264
> SoCs. The implementation mirrors the existing ACPI probe path, parsing
> the nvidia,cmdqv phandle from the SMMU device tree node to associate
> each SMMU with its corresponding CMDQV instance.
> 
> Remove the ACPI dependency from Kconfig as the driver now supports both
> ACPI and device tree initialization through conditional compilation.
> 
> Signed-off-by: Ashish Mhetre <amhetre@...dia.com>

Reviewed-by: Nicolin Chen <nicolinc@...dia.com>

With two nits:

> diff --git a/drivers/iommu/arm/Kconfig b/drivers/iommu/arm/Kconfig
> index ef42bbe07dbe..5fac08b89dee 100644
> --- a/drivers/iommu/arm/Kconfig
> +++ b/drivers/iommu/arm/Kconfig
> @@ -121,7 +121,6 @@ config ARM_SMMU_V3_KUNIT_TEST
>  
>  config TEGRA241_CMDQV
>  	bool "NVIDIA Tegra241 CMDQ-V extension support for ARM SMMUv3"
> -	depends on ACPI

Perhaps:
depends on OF || ACPI

and update the commit message.

> +static void tegra_cmdqv_dt_probe(struct device_node *smmu_node,
> +				 struct arm_smmu_device *smmu)
> +{
> +	struct platform_device *pdev;
> +	struct device_node *np;
> +
> +	np = of_parse_phandle(smmu_node, "nvidia,cmdqv", 0);
> +	if (!np)
> +		return;
> +
> +	pdev = of_find_device_by_node(np);
> +	of_node_put(np);
> +	if (!pdev)
> +		return;
> +
> +	smmu->impl_dev = &pdev->dev;
> +	smmu->options |= ARM_SMMU_OPT_TEGRA241_CMDQV;
> +	dev_info(smmu->dev, "found companion CMDQV device: %s\n",
> +			dev_name(smmu->impl_dev));

	dev_info(smmu->dev, "found companion CMDQV device: %s\n",
		 dev_name(smmu->impl_dev));

Nicolin