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SubjectRe: [PATCH -mm] SWIOTLB: use iommu_is_span_boundary helper function
On Thu,  3 Apr 2008 06:02:35 +0900
FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> wrote:

> iommu_is_span_boundary in lib/iommu-helper.c was exported for PARISC
> IOMMUs (commit 3715863aa142c4f4c5208f5f3e5e9bac06006d2f). SWIOTLB can
> use it instead of the homegrown function.
>
> Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: H. Peter Anvin <hpa@zytor.com>
> Cc: Tony Luck <tony.luck@intel.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> ---
> arch/ia64/Kconfig | 5 ++++-
> arch/x86/Kconfig | 5 ++---
> lib/swiotlb.c | 14 +++-----------
> 3 files changed, 9 insertions(+), 15 deletions(-)
>
> diff --git a/arch/ia64/Kconfig b/arch/ia64/Kconfig
> index 53b8410..6840a13 100644
> --- a/arch/ia64/Kconfig
> +++ b/arch/ia64/Kconfig
> @@ -47,6 +47,9 @@ config MMU
> config SWIOTLB
> bool
>
> +config IOMMU_HELPER
> + bool
> +
> config GENERIC_LOCKBREAK
> bool
> default y
> @@ -624,7 +627,7 @@ config IRQ_PER_CPU
> default y
>
> config IOMMU_HELPER
> - def_bool (IA64_HP_ZX1 || IA64_HP_ZX1_SWIOTLB || IA64_GENERIC)
> + def_bool (IA64_HP_ZX1 || IA64_HP_ZX1_SWIOTLB || IA64_GENERIC || SWIOTLB)
>
> source "arch/ia64/hp/sim/Kconfig"
>
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 1f44517..e6c01c2 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -502,9 +502,6 @@ config CALGARY_IOMMU_ENABLED_BY_DEFAULT
> Calgary anyway, pass 'iommu=calgary' on the kernel command line.
> If unsure, say Y.
>
> -config IOMMU_HELPER
> - def_bool (CALGARY_IOMMU || GART_IOMMU)
> -
> # need this always selected by IOMMU for the VIA workaround
> config SWIOTLB
> bool
> @@ -515,6 +512,8 @@ config SWIOTLB
> access 32-bits of memory can be used on systems with more than
> 3 GB of memory. If unsure, say Y.
>
> +config IOMMU_HELPER
> + def_bool (CALGARY_IOMMU || GART_IOMMU || SWIOTLB)
>
> config NR_CPUS
> int "Maximum number of CPUs (2-255)"
> diff --git a/lib/swiotlb.c b/lib/swiotlb.c
> index 62c9a18..b50c7e0 100644
> --- a/lib/swiotlb.c
> +++ b/lib/swiotlb.c
> @@ -31,6 +31,7 @@
>
> #include <linux/init.h>
> #include <linux/bootmem.h>
> +#include <linux/iommu-helper.h>
>
> #define OFFSET(val,align) ((unsigned long) \
> ( (val) & ( (align) - 1)))
> @@ -282,15 +283,6 @@ address_needs_mapping(struct device *hwdev, dma_addr_t addr)
> return (addr & ~mask) != 0;
> }
>
> -static inline unsigned int is_span_boundary(unsigned int index,
> - unsigned int nslots,
> - unsigned long offset_slots,
> - unsigned long max_slots)
> -{
> - unsigned long offset = (offset_slots + index) & (max_slots - 1);
> - return offset + nslots > max_slots;
> -}
> -
> /*
> * Allocates bounce buffer and returns its kernel virtual address.
> */
> @@ -338,8 +330,8 @@ map_single(struct device *hwdev, char *buffer, size_t size, int dir)
> wrap = index;
>
> do {
> - while (is_span_boundary(index, nslots, offset_slots,
> - max_slots)) {
> + while (iommu_is_span_boundary(index, nslots, offset_slots,
> + max_slots)) {
> index += stride;
> if (index >= io_tlb_nslabs)
> index = 0;

Fair enough.

It's confusing that iommu_is_span_boundary() uses index, nr, shift and
boundary_size whereas is_span_boundary() used index, nslots, offset_slots,
and max_slots. Which one was most accurate, clearer, etc?



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