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SubjectRe: [PATCH v3 1/8] iommu: Add MMIO mapping type
Hi Robin,

Thanks for your update patch I will include it in my next version. But
I'm sorry I do not understand, is your modification an addition or a
substitution to your original patch?

* Robin Murphy <robin.murphy@arm.com> [2016-02-11 15:57:26 +0000]:

> On 11/02/16 00:02, Laurent Pinchart wrote:
> >Hi Niklas,
> >
> >Thank you for the patch.
> >
> >On Wednesday 10 February 2016 01:57:51 Niklas Söderlund wrote:
> >>From: Robin Murphy <robin.murphy@arm.com>
> >>
> >>On some platforms, MMIO regions might need slightly different treatment
> >>compared to mapping regular memory; add the notion of MMIO mappings to
> >>the IOMMU API's memory type flags, so that callers can let the IOMMU
> >>drivers know to do the right thing.
> >>
> >>Signed-off-by: Robin Murphy <robin.murphy@arm.com>
> >>Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> >
> >Answering the question from the cover letter, yes, it's totally fine to pick
> >the ack, that's actually expected.
> >
> >>---
> >> drivers/iommu/io-pgtable-arm.c | 4 +++-
> >> include/linux/iommu.h | 1 +
> >
> >You might be asked to split this patch in two.
>
> Worse than that, you might also be asked to fix it up when the silly author
> remembers that he did this on a stage-2-only ARM SMMU, and the attributes
> for the stage 1 tables that the IPMMU uses are in a different code path:
>
> --->8---
> diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
> index 5b5c299..7622c6e 100644
> --- a/drivers/iommu/io-pgtable-arm.c
> +++ b/drivers/iommu/io-pgtable-arm.c
> @@ -354,7 +354,10 @@ static arm_lpae_iopte arm_lpae_prot_to_pte(struct
> arm_lpae_io_pgtable *data,
> if (!(prot & IOMMU_WRITE) && (prot & IOMMU_READ))
> pte |= ARM_LPAE_PTE_AP_RDONLY;
>
> - if (prot & IOMMU_CACHE)
> + if (prot & IOMMU_MMIO)
> + pte |= (ARM_LPAE_MAIR_ATTR_IDX_DEV
> + << ARM_LPAE_PTE_ATTRINDX_SHIFT);
> + else if (prot & IOMMU_CACHE)
> pte |= (ARM_LPAE_MAIR_ATTR_IDX_CACHE
> << ARM_LPAE_PTE_ATTRINDX_SHIFT);
> } else {
> --->8---
>
> Sorry for the bother,
> Robin.
>
> >> 2 files changed, 4 insertions(+), 1 deletion(-)
> >>
> >>diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
> >>index 381ca5a..3ff4f87 100644
> >>--- a/drivers/iommu/io-pgtable-arm.c
> >>+++ b/drivers/iommu/io-pgtable-arm.c
> >>@@ -364,7 +364,9 @@ static arm_lpae_iopte arm_lpae_prot_to_pte(struct
> >>arm_lpae_io_pgtable *data, pte |= ARM_LPAE_PTE_HAP_READ;
> >> if (prot & IOMMU_WRITE)
> >> pte |= ARM_LPAE_PTE_HAP_WRITE;
> >>- if (prot & IOMMU_CACHE)
> >>+ if (prot & IOMMU_MMIO)
> >>+ pte |= ARM_LPAE_PTE_MEMATTR_DEV;
> >>+ else if (prot & IOMMU_CACHE)
> >> pte |= ARM_LPAE_PTE_MEMATTR_OIWB;
> >> else
> >> pte |= ARM_LPAE_PTE_MEMATTR_NC;
> >>diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> >>index a5c539f..34b6432 100644
> >>--- a/include/linux/iommu.h
> >>+++ b/include/linux/iommu.h
> >>@@ -30,6 +30,7 @@
> >> #define IOMMU_WRITE (1 << 1)
> >> #define IOMMU_CACHE (1 << 2) /* DMA cache coherency */
> >> #define IOMMU_NOEXEC (1 << 3)
> >>+#define IOMMU_MMIO (1 << 4) /* e.g. things like MSI doorbells */
> >>
> >> struct iommu_ops;
> >> struct iommu_group;
> >
>

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