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    Subject[PATCH v1 4/4] iommu/tegra: gart: Optimize map/unmap
    Date
    Currently GART writes one page entry at a time. More optimal would be to
    aggregate the writes and flush BUS buffer in the end, this gives map/unmap
    10-40% (depending on size of mapping) performance boost compared to a
    flushing after each entry update.

    Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
    ---
    drivers/iommu/tegra-gart.c | 63 +++++++++++++++++++++++++++++++++++-----------
    1 file changed, 48 insertions(+), 15 deletions(-)

    diff --git a/drivers/iommu/tegra-gart.c b/drivers/iommu/tegra-gart.c
    index 4a0607669d34..9f59f5f17661 100644
    --- a/drivers/iommu/tegra-gart.c
    +++ b/drivers/iommu/tegra-gart.c
    @@ -36,7 +36,7 @@
    #define GART_APERTURE_SIZE SZ_32M

    /* bitmap of the page sizes currently supported */
    -#define GART_IOMMU_PGSIZES (SZ_4K)
    +#define GART_IOMMU_PGSIZES GENMASK(24, 12)

    #define GART_REG_BASE 0x24
    #define GART_CONFIG (0x24 - GART_REG_BASE)
    @@ -269,25 +269,21 @@ static void gart_iommu_domain_free(struct iommu_domain *domain)
    kfree(gart_domain);
    }

    -static int gart_iommu_map(struct iommu_domain *domain, unsigned long iova,
    - phys_addr_t pa, size_t bytes, int prot)
    +static int gart_iommu_map_page(struct gart_device *gart,
    + unsigned long iova,
    + phys_addr_t pa)
    {
    - struct gart_domain *gart_domain = to_gart_domain(domain);
    - struct gart_device *gart = gart_domain->gart;
    unsigned long flags;
    unsigned long pfn;
    unsigned long pte;

    - if (!gart_iova_range_valid(gart, iova, bytes))
    - return -EINVAL;
    -
    - spin_lock_irqsave(&gart->pte_lock, flags);
    pfn = __phys_to_pfn(pa);
    if (!pfn_valid(pfn)) {
    dev_err(gart->dev, "Invalid page: %pa\n", &pa);
    - spin_unlock_irqrestore(&gart->pte_lock, flags);
    return -EINVAL;
    }
    +
    + spin_lock_irqsave(&gart->pte_lock, flags);
    if (gart_debug) {
    pte = gart_read_pte(gart, iova);
    if (pte & GART_ENTRY_PHYS_ADDR_VALID) {
    @@ -297,8 +293,41 @@ static int gart_iommu_map(struct iommu_domain *domain, unsigned long iova,
    }
    }
    gart_set_pte(gart, iova, GART_PTE(pfn));
    + spin_unlock_irqrestore(&gart->pte_lock, flags);
    +
    + return 0;
    +}
    +
    +static int gart_iommu_map(struct iommu_domain *domain, unsigned long iova,
    + phys_addr_t pa, size_t bytes, int prot)
    +{
    + struct gart_domain *gart_domain = to_gart_domain(domain);
    + struct gart_device *gart = gart_domain->gart;
    + size_t mapped;
    + int ret = -1;
    +
    + if (!gart_iova_range_valid(gart, iova, bytes))
    + return -EINVAL;
    +
    + for (mapped = 0; mapped < bytes; mapped += GART_PAGE_SIZE) {
    + ret = gart_iommu_map_page(gart, iova + mapped, pa + mapped);
    + if (ret)
    + break;
    + }
    +
    FLUSH_GART_REGS(gart);
    + return ret;
    +}
    +
    +static int gart_iommu_unmap_page(struct gart_device *gart,
    + unsigned long iova)
    +{
    + unsigned long flags;
    +
    + spin_lock_irqsave(&gart->pte_lock, flags);
    + gart_set_pte(gart, iova, 0);
    spin_unlock_irqrestore(&gart->pte_lock, flags);
    +
    return 0;
    }

    @@ -307,16 +336,20 @@ static size_t gart_iommu_unmap(struct iommu_domain *domain, unsigned long iova,
    {
    struct gart_domain *gart_domain = to_gart_domain(domain);
    struct gart_device *gart = gart_domain->gart;
    - unsigned long flags;
    + size_t unmapped;
    + int ret;

    if (!gart_iova_range_valid(gart, iova, bytes))
    return 0;

    - spin_lock_irqsave(&gart->pte_lock, flags);
    - gart_set_pte(gart, iova, 0);
    + for (unmapped = 0; unmapped < bytes; unmapped += GART_PAGE_SIZE) {
    + ret = gart_iommu_unmap_page(gart, iova + unmapped);
    + if (ret)
    + break;
    + }
    +
    FLUSH_GART_REGS(gart);
    - spin_unlock_irqrestore(&gart->pte_lock, flags);
    - return bytes;
    + return unmapped;
    }

    static phys_addr_t gart_iommu_iova_to_phys(struct iommu_domain *domain,
    --
    2.16.3
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