target/linux/generic/pending-4.14/341-MIPS-mm-remove-no-op-dma_map_ops-where-possible.patch

   1 From: Felix Fietkau <nbd@nbd.name>
   2 Date: Tue, 5 Dec 2017 12:46:01 +0100
   3 Subject: [PATCH] MIPS: mm: remove no-op dma_map_ops where possible
   4
   5 If no post-DMA flush is required, and the platform does not provide
   6 plat_unmap_dma_mem(), there is no need to include unmap or sync_for_cpu
   7 ops.
   8
   9 With this patch they are compiled out to improve icache footprint
  10 on devices that handle lots of DMA traffic (especially network routers).
  11
  12 Signed-off-by: Felix Fietkau <nbd@nbd.name>
  13 ---
  14
  15 --- a/arch/mips/Kconfig
  16 +++ b/arch/mips/Kconfig
  17 @@ -220,6 +220,7 @@ config BMIPS_GENERIC
  18         select BRCMSTB_L2_IRQ
  19         select IRQ_MIPS_CPU
  20         select DMA_NONCOHERENT
  21 +       select DMA_UNMAP_POST_FLUSH
  22         select SYS_SUPPORTS_32BIT_KERNEL
  23         select SYS_SUPPORTS_LITTLE_ENDIAN
  24         select SYS_SUPPORTS_BIG_ENDIAN
  25 @@ -345,6 +346,7 @@ config MACH_JAZZ
  26         select CSRC_R4K
  27         select DEFAULT_SGI_PARTITION if CPU_BIG_ENDIAN
  28         select GENERIC_ISA_DMA
  29 +       select DMA_UNMAP_POST_FLUSH
  30         select HAVE_PCSPKR_PLATFORM
  31         select IRQ_MIPS_CPU
  32         select I8253
  33 @@ -1127,6 +1129,9 @@ config DMA_NONCOHERENT
  34         bool
  35         select NEED_DMA_MAP_STATE
  36
  37 +config DMA_UNMAP_POST_FLUSH
  38 +       bool
  39 +
  40  config NEED_DMA_MAP_STATE
  41         bool
  42
  43 @@ -1651,6 +1656,7 @@ config CPU_R10000
  44         select CPU_SUPPORTS_64BIT_KERNEL
  45         select CPU_SUPPORTS_HIGHMEM
  46         select CPU_SUPPORTS_HUGEPAGES
  47 +       select DMA_UNMAP_POST_FLUSH
  48         help
  49           MIPS Technologies R10000-series processors.
  50
  51 @@ -1899,9 +1905,11 @@ config SYS_HAS_CPU_MIPS32_R3_5
  52         bool
  53
  54  config SYS_HAS_CPU_MIPS32_R5
  55 +       select DMA_UNMAP_POST_FLUSH
  56         bool
  57
  58  config SYS_HAS_CPU_MIPS32_R6
  59 +       select DMA_UNMAP_POST_FLUSH
  60         bool
  61
  62  config SYS_HAS_CPU_MIPS64_R1
  63 @@ -1911,6 +1919,7 @@ config SYS_HAS_CPU_MIPS64_R2
  64         bool
  65
  66  config SYS_HAS_CPU_MIPS64_R6
  67 +       select DMA_UNMAP_POST_FLUSH
  68         bool
  69
  70  config SYS_HAS_CPU_R3000
  71 --- a/arch/mips/mm/dma-default.c
  72 +++ b/arch/mips/mm/dma-default.c
  73 @@ -267,8 +267,9 @@ static inline void __dma_sync(struct pag
  74         } while (left);
  75  }
  76
  77 -static void mips_dma_unmap_page(struct device *dev, dma_addr_t dma_addr,
  78 -       size_t size, enum dma_data_direction direction, unsigned long attrs)
  79 +static void __maybe_unused
  80 +mips_dma_unmap_page(struct device *dev, dma_addr_t dma_addr, size_t size,
  81 +                   enum dma_data_direction direction, unsigned long attrs)
  82  {
  83         if (cpu_needs_post_dma_flush(dev) && !(attrs & DMA_ATTR_SKIP_CPU_SYNC))
  84                 __dma_sync(dma_addr_to_page(dev, dma_addr),
  85 @@ -308,9 +309,10 @@ static dma_addr_t mips_dma_map_page(stru
  86         return plat_map_dma_mem_page(dev, page) + offset;
  87  }
  88
  89 -static void mips_dma_unmap_sg(struct device *dev, struct scatterlist *sglist,
  90 -       int nhwentries, enum dma_data_direction direction,
  91 -       unsigned long attrs)
  92 +static void __maybe_unused
  93 +mips_dma_unmap_sg(struct device *dev, struct scatterlist *sglist,
  94 +                 int nhwentries, enum dma_data_direction direction,
  95 +                 unsigned long attrs)
  96  {
  97         int i;
  98         struct scatterlist *sg;
  99 @@ -325,8 +327,9 @@ static void mips_dma_unmap_sg(struct dev
 100         }
 101  }
 102
 103 -static void mips_dma_sync_single_for_cpu(struct device *dev,
 104 -       dma_addr_t dma_handle, size_t size, enum dma_data_direction direction)
 105 +static void __maybe_unused
 106 +mips_dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_handle,
 107 +                            size_t size, enum dma_data_direction direction)
 108  {
 109         if (cpu_needs_post_dma_flush(dev))
 110                 __dma_sync(dma_addr_to_page(dev, dma_handle),
 111 @@ -342,9 +345,9 @@ static void mips_dma_sync_single_for_dev
 112                            dma_handle & ~PAGE_MASK, size, direction);
 113  }
 114
 115 -static void mips_dma_sync_sg_for_cpu(struct device *dev,
 116 -       struct scatterlist *sglist, int nelems,
 117 -       enum dma_data_direction direction)
 118 +static void __maybe_unused
 119 +mips_dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sglist,
 120 +                        int nelems, enum dma_data_direction direction)
 121  {
 122         int i;
 123         struct scatterlist *sg;
 124 @@ -394,12 +397,14 @@ static const struct dma_map_ops mips_def
 125         .free = mips_dma_free_coherent,
 126         .mmap = mips_dma_mmap,
 127         .map_page = mips_dma_map_page,
 128 -       .unmap_page = mips_dma_unmap_page,
 129         .map_sg = mips_dma_map_sg,
 130 +#ifdef CONFIG_DMA_UNMAP_POST_FLUSH
 131 +       .unmap_page = mips_dma_unmap_page,
 132         .unmap_sg = mips_dma_unmap_sg,
 133         .sync_single_for_cpu = mips_dma_sync_single_for_cpu,
 134 -       .sync_single_for_device = mips_dma_sync_single_for_device,
 135         .sync_sg_for_cpu = mips_dma_sync_sg_for_cpu,
 136 +#endif
 137 +       .sync_single_for_device = mips_dma_sync_single_for_device,
 138         .sync_sg_for_device = mips_dma_sync_sg_for_device,
 139         .dma_supported = mips_dma_supported
 140  };