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Re: [PATCH 2/7 v2] powerpc/dma-mapping: override dma_get_page_shift

From Alexey Kardashevskiy <aik@ozlabs.ru>
Newsgroups linux.kernel
Subject Re: [PATCH 2/7 v2] powerpc/dma-mapping: override dma_get_page_shift
Date 2015-10-27 07:10 +0100
Message-ID <qo5Ch-1Ga-3@gated-at.bofh.it> (permalink)
References <qmRBo-4gB-11@gated-at.bofh.it> <qmRBp-4gB-25@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On 10/24/2015 07:57 AM, Nishanth Aravamudan wrote:
> On Power, the kernel's page size can differ from the IOMMU's page size,
> so we need to override the generic implementation, which always returns
> the kernel's page size. Lookup the IOMMU's page size from struct
> iommu_table, if available. Fallback to the kernel's page size,
> otherwise.
>
> Signed-off-by: Nishanth Aravamudan <nacc@linux.vnet.ibm.com>
> ---
>   arch/powerpc/include/asm/dma-mapping.h | 3 +++
>   arch/powerpc/kernel/dma.c              | 9 +++++++++
>   2 files changed, 12 insertions(+)
>
> diff --git a/arch/powerpc/include/asm/dma-mapping.h b/arch/powerpc/include/asm/dma-mapping.h
> index 7f522c0..c5638f4 100644
> --- a/arch/powerpc/include/asm/dma-mapping.h
> +++ b/arch/powerpc/include/asm/dma-mapping.h
> @@ -125,6 +125,9 @@ static inline void set_dma_offset(struct device *dev, dma_addr_t off)
>   #define HAVE_ARCH_DMA_SET_MASK 1
>   extern int dma_set_mask(struct device *dev, u64 dma_mask);
>
> +#define HAVE_ARCH_DMA_GET_PAGE_SHIFT 1
> +extern unsigned long dma_get_page_shift(struct device *dev);
> +
>   #include <asm-generic/dma-mapping-common.h>
>
>   extern int __dma_set_mask(struct device *dev, u64 dma_mask);
> diff --git a/arch/powerpc/kernel/dma.c b/arch/powerpc/kernel/dma.c
> index 59503ed..e805af2 100644
> --- a/arch/powerpc/kernel/dma.c
> +++ b/arch/powerpc/kernel/dma.c
> @@ -335,6 +335,15 @@ int dma_set_mask(struct device *dev, u64 dma_mask)
>   }
>   EXPORT_SYMBOL(dma_set_mask);
>
> +unsigned long dma_get_page_shift(struct device *dev)
> +{
> +	struct iommu_table *tbl = get_iommu_table_base(dev);
> +	if (tbl)
> +		return tbl->it_page_shift;


All PCI devices have this initialized on POWER (at least, our, IBM's POWER) 
so 4K will always be returned here while in the case of 
(get_dma_ops(dev)==&dma_direct_ops) it could actually return PAGE_SHIFT. Is 
4K still preferred value to return here?



> +	return PAGE_SHIFT;
> +}
> +EXPORT_SYMBOL(dma_get_page_shift);
> +
>   u64 __dma_get_required_mask(struct device *dev)
>   {
>   	struct dma_map_ops *dma_ops = get_dma_ops(dev);
>


-- 
Alexey
--
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Thread

[PATCH 0/5 v3] Fix NVMe driver support on Power with 32-bit DMA Nishanth Aravamudan <nacc@linux.vnet.ibm.com> - 2015-10-23 23:00 +0200
  Re: [PATCH 0/5 v3] Fix NVMe driver support on Power with 32-bit DMA Nishanth Aravamudan <nacc@linux.vnet.ibm.com> - 2015-10-23 23:00 +0200
  [PATCH 1/7 v3] dma-mapping: add generic dma_get_page_shift API Nishanth Aravamudan <nacc@linux.vnet.ibm.com> - 2015-10-23 23:00 +0200
  [PATCH 2/7 v2] powerpc/dma-mapping: override dma_get_page_shift Nishanth Aravamudan <nacc@linux.vnet.ibm.com> - 2015-10-23 23:00 +0200
    Re: [PATCH 2/7 v2] powerpc/dma-mapping: override dma_get_page_shift Alexey Kardashevskiy <aik@ozlabs.ru> - 2015-10-27 07:10 +0100
      Re: [PATCH 2/7 v2] powerpc/dma-mapping: override dma_get_page_shift "Busch, Keith" <keith.busch@intel.com> - 2015-10-27 15:10 +0100
      Re: [PATCH 2/7 v2] powerpc/dma-mapping: override dma_get_page_shift Nishanth Aravamudan <nacc@linux.vnet.ibm.com> - 2015-10-27 23:30 +0100
        Re: [PATCH 2/7 v2] powerpc/dma-mapping: override dma_get_page_shift Alexey Kardashevskiy <aik@ozlabs.ru> - 2015-10-28 02:10 +0100
          Re: [PATCH 2/7 v2] powerpc/dma-mapping: override dma_get_page_shift Nishanth Aravamudan <nacc@linux.vnet.ibm.com> - 2015-10-28 03:00 +0100
            Re: [PATCH 2/7 v2] powerpc/dma-mapping: override dma_get_page_shift Benjamin Herrenschmidt <benh@kernel.crashing.org> - 2015-10-28 03:30 +0100
              Re: [PATCH 2/7 v2] powerpc/dma-mapping: override dma_get_page_shift Nishanth Aravamudan <nacc@linux.vnet.ibm.com> - 2015-10-28 03:40 +0100
                Re: [PATCH 2/7 v2] powerpc/dma-mapping: override dma_get_page_shift Benjamin Herrenschmidt <benh@kernel.crashing.org> - 2015-10-28 04:30 +0100
  [PATCH 4/7 v2] pseries/iommu: implement DDW-aware dma_get_page_shift Nishanth Aravamudan <nacc@linux.vnet.ibm.com> - 2015-10-23 23:00 +0200
    Re: [PATCH 4/7 v2] pseries/iommu: implement DDW-aware  dma_get_page_shift Alexey Kardashevskiy <aik@ozlabs.ru> - 2015-10-27 07:00 +0100
      Re: [PATCH 4/7 v2] pseries/iommu: implement DDW-aware  dma_get_page_shift Nishanth Aravamudan <nacc@linux.vnet.ibm.com> - 2015-10-27 23:30 +0100
  [RFC PATCH 6/7] sparc/dma-mapping: override dma_get_page_shift Nishanth Aravamudan <nacc@linux.vnet.ibm.com> - 2015-10-23 23:10 +0200
  [PATCH 7/7 v2] drivers/nvme: default to the IOMMU page size Nishanth Aravamudan <nacc@linux.vnet.ibm.com> - 2015-10-23 23:10 +0200
  [PATCH 5/7] [RFC PATCH 5/7] sparc: rename kernel/iommu_common.h ->  include/asm/iommu_common.h Nishanth Aravamudan <nacc@linux.vnet.ibm.com> - 2015-10-23 23:10 +0200
    Re: [PATCH 5/7] [RFC PATCH 5/7] sparc: rename kernel/iommu_common.h  -> include/asm/iommu_common.h Nishanth Aravamudan <nacc@linux.vnet.ibm.com> - 2015-10-23 23:10 +0200
  Re: [PATCH 0/5 v3] Fix NVMe driver support on Power with 32-bit DMA David Miller <davem@davemloft.net> - 2015-10-27 02:20 +0100
    Re: [PATCH 0/5 v3] Fix NVMe driver support on Power with 32-bit DMA Nishanth Aravamudan <nacc@linux.vnet.ibm.com> - 2015-10-27 23:30 +0100
      Re: [PATCH 0/5 v3] Fix NVMe driver support on Power with 32-bit DMA "Busch, Keith" <keith.busch@intel.com> - 2015-10-27 23:40 +0100
        Re: [PATCH 0/5 v3] Fix NVMe driver support on Power with 32-bit DMA David Miller <davem@davemloft.net> - 2015-10-28 01:40 +0100
          Re: [PATCH 0/5 v3] Fix NVMe driver support on Power with 32-bit DMA "Busch, Keith" <keith.busch@intel.com> - 2015-10-28 15:00 +0100
            Re: [PATCH 0/5 v3] Fix NVMe driver support on Power with 32-bit DMA Christoph Hellwig <hch@infradead.org> - 2015-10-29 13:00 +0100
              Re: [PATCH 0/5 v3] Fix NVMe driver support on Power with 32-bit DMA Nishanth Aravamudan <nacc@linux.vnet.ibm.com> - 2015-10-29 17:00 +0100
                Re: [PATCH 0/5 v3] Fix NVMe driver support on Power with 32-bit DMA "Busch, Keith" <keith.busch@intel.com> - 2015-10-29 18:30 +0100
                [PATCH 1/1 v3] drivers/nvme: default to 4k device page size Nishanth Aravamudan <nacc@linux.vnet.ibm.com> - 2015-10-30 22:40 +0100
                Re: [PATCH 1/1 v3] drivers/nvme: default to 4k device page size Keith Busch <keith.busch@intel.com> - 2015-10-30 22:50 +0100
                Re: [PATCH 1/1 v3] drivers/nvme: default to 4k device page size Nishanth Aravamudan <nacc@linux.vnet.ibm.com> - 2015-10-30 23:20 +0100
                Re: [PATCH 0/5 v3] Fix NVMe driver support on Power with 32-bit DMA David Miller <davem@davemloft.net> - 2015-10-30 02:40 +0100
                Re: [PATCH 0/5 v3] Fix NVMe driver support on Power with 32-bit DMA Nishanth Aravamudan <nacc@linux.vnet.ibm.com> - 2015-10-30 22:40 +0100
      Re: [PATCH 0/5 v3] Fix NVMe driver support on Power with 32-bit DMA Julian Calaby <julian.calaby@gmail.com> - 2015-10-28 00:00 +0100
        Re: [PATCH 0/5 v3] Fix NVMe driver support on Power with 32-bit DMA Julian Calaby <julian.calaby@gmail.com> - 2015-10-28 00:50 +0100
          Re: [PATCH 0/5 v3] Fix NVMe driver support on Power with 32-bit DMA Benjamin Herrenschmidt <benh@kernel.crashing.org> - 2015-10-28 01:40 +0100
          Re: [PATCH 0/5 v3] Fix NVMe driver support on Power with 32-bit DMA David Miller <davem@davemloft.net> - 2015-10-28 01:50 +0100
        Re: [PATCH 0/5 v3] Fix NVMe driver support on Power with 32-bit DMA Nishanth Aravamudan <nacc@linux.vnet.ibm.com> - 2015-10-28 00:50 +0100
      Re: [PATCH 0/5 v3] Fix NVMe driver support on Power with 32-bit DMA David Miller <davem@davemloft.net> - 2015-10-28 01:40 +0100
        Re: [PATCH 0/5 v3] Fix NVMe driver support on Power with 32-bit DMA Nishanth Aravamudan <nacc@linux.vnet.ibm.com> - 2015-10-28 03:00 +0100

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