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From: Nicolin Chen <nicolinc@nvidia.com>
To: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
Cc: <iommu@lists.linux.dev>, <linux-arm-kernel@lists.infradead.org>,
	<robin.murphy@arm.com>, <will@kernel.org>, <joro@8bytes.org>,
	<jgg@nvidia.com>, <ryan.roberts@arm.com>, <kevin.tian@intel.com>,
	<mshavit@google.com>, <eric.auger@redhat.com>,
	<joao.m.martins@oracle.com>, <jiangkunkun@huawei.com>,
	<zhukeqian1@huawei.com>, <linuxarm@huawei.com>
Subject: Re: [PATCH v5 3/6] iommu/arm-smmu-v3: Add feature detection for HTTU
Date: Thu, 6 Jun 2024 16:10:52 -0700	[thread overview]
Message-ID: <ZmJB/IjP+RVTKp/5@Asurada-Nvidia> (raw)
In-Reply-To: <20240606133302.17540-4-shameerali.kolothum.thodi@huawei.com>

Hi Shameer,

Some nitpicking inline.

On Thu, Jun 06, 2024 at 02:32:59PM +0100, Shameer Kolothum wrote:

> 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 e30ce55ed1af..c05a74aa52a4 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> @@ -3738,6 +3738,29 @@ static void arm_smmu_device_iidr_probe(struct arm_smmu_device *smmu)
>         }
>  }
> 
> +static void arm_smmu_get_httu(struct arm_smmu_device *smmu, u32 reg)

Following the other helper arm_smmu_device_iidr_probe, how about
arm_smmu_device_httu_probe?

And we could pass in FIELD_GET(IDR0_HTTU, reg) too?

> +{
> +       u32 fw_features = smmu->features & (ARM_SMMU_FEAT_HA | ARM_SMMU_FEAT_HD);
> +       u32 httu = FIELD_GET(IDR0_HTTU, reg);
> +       u32 features = 0;

How about "hw_feats" v.s. "fw_feats"?

> +
> +       switch (httu) {
> +       case IDR0_HTTU_ACCESS_DIRTY:
> +               features |= ARM_SMMU_FEAT_HD;
> +               fallthrough;
> +       case IDR0_HTTU_ACCESS:
> +               features |= ARM_SMMU_FEAT_HA;
> +       }
> +
> +       if (smmu->dev->of_node)
> +               smmu->features |= features;
> +       else if (features != fw_features)
> +               /* ACPI IORT sets the HTTU bits */
> +               dev_warn(smmu->dev,
> +                        "IDR0.HTTU(0x%x) overridden by FW configuration (0x%x)\n",
> +                         httu, fw_features);

httu and fw_features have different shifts -- could be odd to see:
	IDR0.HTTU(0x2) overridden by FW configuration (0x600000)

FIELD_GET(ACPI_IORT_SMMU_V3_HTTU_OVERRIDE, iort_smmu->flags) seems
to be overcomplicated to reference? So, how about just features?
+			"IDR0.HTTU features (0x%x) overridden by FW configuration (0x%x)\n",

Thanks
Nicolin

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  reply	other threads:[~2024-06-06 23:27 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-06-06 13:32 [PATCH v5 0/6] Add IOMMUFD dirty tracking support for SMMUv3 Shameer Kolothum
2024-06-06 13:32 ` [PATCH v5 1/6] iommu/arm-smmu-v3: Factor out a common domain alloc Shameer Kolothum
2024-06-06 18:08   ` Jason Gunthorpe
2024-06-06 22:12   ` Nicolin Chen
2024-06-06 13:32 ` [PATCH v5 2/6] iommu/arm-smmu-v3: Add support for domain_alloc_user fn Shameer Kolothum
2024-06-06 22:13   ` Nicolin Chen
2024-06-06 13:32 ` [PATCH v5 3/6] iommu/arm-smmu-v3: Add feature detection for HTTU Shameer Kolothum
2024-06-06 23:10   ` Nicolin Chen [this message]
2024-06-07  8:04     ` Shameerali Kolothum Thodi
2024-06-07 21:21       ` Nicolin Chen
2024-06-06 13:33 ` [PATCH v5 4/6] iommu/io-pgtable-arm: Add read_and_clear_dirty() support Shameer Kolothum
2024-06-06 13:33 ` [PATCH v5 5/6] iommu/arm-smmu-v3: Add support for dirty tracking in domain alloc Shameer Kolothum
2024-06-06 23:39   ` Nicolin Chen
2024-06-06 13:33 ` [PATCH v5 6/6] iommu/arm-smmu-v3: Enable HTTU for stage1 with io-pgtable mapping Shameer Kolothum
2024-06-06 23:47   ` Nicolin Chen
2024-06-07  9:49 ` [PATCH v5 0/6] Add IOMMUFD dirty tracking support for SMMUv3 Tian, Kevin

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