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    SubjectRe: [PATCH 0/5] FlexRM support in VFIO platform
    On Wed, Jul 19, 2017 at 4:27 PM, Robin Murphy <robin.murphy@arm.com> wrote:
    > On 19/07/17 10:33, Anup Patel wrote:
    >> This patchset primarily adds Broadcom FlexRM reset module for
    >> VFIO platform driver. We also have minor improvments in IOMMU
    >> and VFIO driver to allow VFIO no-IOMMU mode access to FlexRM.
    >
    > I'm struggling to understand the IOMMU changes here - what's the
    > FlexRM's hardware relationship with the IOMMU, and how is it different
    > from any other device? Furthermore, if there *is* a relevant IOMMU
    > present, why would no-IOMMU mode need to be involved at all?

    We want to have FlexRM device accessible from user-space
    using VFIO platform with and without IOMMU.

    Currently, if IOMMU ops are available for platform bus then
    I cannot access FlexRM device using VFIO no-IOMMU mode.

    Since, SMMU can bypass transactions which do not match
    any SMRs, we should allow no-IOMMU mode for devices
    when IOMMU group is not available.

    Regards,
    Anup

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