Re: [PATCH V7 2/4] iommu/arm-smmu-v3: Add device-tree support for CMDQV driver

[Ashish Mhetre]

On 12/18/2025 2:13 AM, Jon Hunter wrote:
> On 15/12/2025 06:48, Ashish Mhetre wrote:
> > Add device tree support to the CMDQV driver to enable usage on Tegra264
> > SoCs. The implementation parses the nvidia,cmdqv phandle from the SMMU
> > device tree node to associate each SMMU with its corresponding CMDQV
> > instance based on compatible string.
> >
> > Reviewed-by: Nicolin Chen <nicolinc@xxxxxxxxxx>
> > Signed-off-by: Ashish Mhetre <amhetre@xxxxxxxxxx>
> > ---
> >   drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 32 +++++++++++++++++++++
> >   1 file changed, 32 insertions(+)
> >
> > diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c 
> > b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> > index dad3c0cb800b..0cd0013200f3 100644
> > --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> > +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> > @@ -4530,6 +4530,35 @@ static int arm_smmu_device_hw_probe(struct 
> > arm_smmu_device *smmu)
> >       return 0;
> >   }
> >   +#ifdef CONFIG_TEGRA241_CMDQV
> > +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;
> > +
> > +    /* Tegra241 CMDQV driver is responsible for put_device() */
> > +    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));
>
> This seems a bit noisy. dev_dbg?

This info print is similar to what is there in ACPI path as well.
It's only a single print per SMMU at boot time. Should I still change
it to dev_dbg?

> > +}
> > +#else
> > +static void tegra_cmdqv_dt_probe(struct device_node *smmu_node,
> > +                 struct arm_smmu_device *smmu)
> > +{
> > +}
> > +#endif
> > +
> >   #ifdef CONFIG_ACPI
> >   #ifdef CONFIG_TEGRA241_CMDQV
> >   static void acpi_smmu_dsdt_probe_tegra241_cmdqv(struct 
> > acpi_iort_node *node,
> > @@ -4635,6 +4664,9 @@ static int arm_smmu_device_dt_probe(struct 
> > platform_device *pdev,
> >       if (of_dma_is_coherent(dev->of_node))
> >           smmu->features |= ARM_SMMU_FEAT_COHERENCY;
> >   +    if (of_device_is_compatible(dev->of_node, 
> > "nvidia,tegra264-smmu"))
> > +        tegra_cmdqv_dt_probe(dev->of_node, smmu);
> > +
> >       return ret;
> >   }