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

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Message-ID: <ac51c86e-775f-46c3-8767-c373d68c5522@nvidia.com>
Date: Mon, 3 Nov 2025 18:36:16 +0530
From: Ashish Mhetre <amhetre@...dia.com>
To: Nicolin Chen <nicolinc@...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 10/31/2025 10:59 PM, Nicolin Chen wrote:
> 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:

Thanks Nic, I'll address these in next version and add reviewed by.
>> 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.

Sure, I will fix this in V2.
>> +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));

Ack,  I'll fix this in next version
> Nicolin