7 config NEED_SG_DMA_LENGTH
10 config NEED_DMA_MAP_STATE
13 config ARCH_DMA_ADDR_T_64BIT
14 def_bool 64BIT || PHYS_ADDR_T_64BIT
16 config ARCH_HAS_DMA_COHERENCE_H
19 config ARCH_HAS_DMA_SET_MASK
22 config DMA_DECLARE_COHERENT
25 config ARCH_HAS_SETUP_DMA_OPS
28 config ARCH_HAS_TEARDOWN_DMA_OPS
31 config ARCH_HAS_SYNC_DMA_FOR_DEVICE
34 config ARCH_HAS_SYNC_DMA_FOR_CPU
36 select NEED_DMA_MAP_STATE
38 config ARCH_HAS_SYNC_DMA_FOR_CPU_ALL
41 config ARCH_HAS_DMA_COHERENT_TO_PFN
44 config ARCH_HAS_DMA_MMAP_PGPROT
47 config DMA_NONCOHERENT_CACHE_SYNC
56 select NEED_DMA_MAP_STATE
62 config DMA_DIRECT_REMAP
67 bool "DMA Contiguous Memory Allocator"
68 depends on HAVE_DMA_CONTIGUOUS && CMA
70 This enables the Contiguous Memory Allocator which allows drivers
71 to allocate big physically-contiguous blocks of memory for use with
72 hardware components that do not support I/O map nor scatter-gather.
74 You can disable CMA by specifying "cma=0" on the kernel's command
77 For more information see <include/linux/dma-contiguous.h>.
81 comment "Default contiguous memory area size:"
83 config CMA_SIZE_MBYTES
84 int "Size in Mega Bytes"
85 depends on !CMA_SIZE_SEL_PERCENTAGE
89 Defines the size (in MiB) of the default memory area for Contiguous
90 Memory Allocator. If the size of 0 is selected, CMA is disabled by
91 default, but it can be enabled by passing cma=size[MG] to the kernel.
94 config CMA_SIZE_PERCENTAGE
95 int "Percentage of total memory"
96 depends on !CMA_SIZE_SEL_MBYTES
100 Defines the size of the default memory area for Contiguous Memory
101 Allocator as a percentage of the total memory in the system.
102 If 0 percent is selected, CMA is disabled by default, but it can be
103 enabled by passing cma=size[MG] to the kernel.
106 prompt "Selected region size"
107 default CMA_SIZE_SEL_MBYTES
109 config CMA_SIZE_SEL_MBYTES
110 bool "Use mega bytes value only"
112 config CMA_SIZE_SEL_PERCENTAGE
113 bool "Use percentage value only"
115 config CMA_SIZE_SEL_MIN
116 bool "Use lower value (minimum)"
118 config CMA_SIZE_SEL_MAX
119 bool "Use higher value (maximum)"
124 int "Maximum PAGE_SIZE order of alignment for contiguous buffers"
128 DMA mapping framework by default aligns all buffers to the smallest
129 PAGE_SIZE order which is greater than or equal to the requested buffer
130 size. This works well for buffers up to a few hundreds kilobytes, but
131 for larger buffers it just a memory waste. With this parameter you can
132 specify the maximum PAGE_SIZE order for contiguous buffers. Larger
133 buffers will be aligned only to this specified order. The order is
134 expressed as a power of two multiplied by the PAGE_SIZE.
136 For example, if your system defaults to 4KiB pages, the order value
137 of 8 means that the buffers will be aligned up to 1MiB only.
139 If unsure, leave the default value "8".
144 bool "Enable debugging of DMA-API usage"
145 select NEED_DMA_MAP_STATE
147 Enable this option to debug the use of the DMA API by device drivers.
148 With this option you will be able to detect common bugs in device
149 drivers like double-freeing of DMA mappings or freeing mappings that
150 were never allocated.
152 This also attempts to catch cases where a page owned by DMA is
153 accessed by the cpu in a way that could cause data corruption. For
154 example, this enables cow_user_page() to check that the source page is
157 This option causes a performance degradation. Use only if you want to
158 debug device drivers and dma interactions.
162 config DMA_API_DEBUG_SG
163 bool "Debug DMA scatter-gather usage"
165 depends on DMA_API_DEBUG
167 Perform extra checking that callers of dma_map_sg() have respected the
168 appropriate segment length/boundary limits for the given device when
169 preparing DMA scatterlists.
171 This is particularly likely to have been overlooked in cases where the
172 dma_map_sg() API is used for general bulk mapping of pages rather than
173 preparing literal scatter-gather descriptors, where there is a risk of
174 unexpected behaviour from DMA API implementations if the scatterlist
175 is technically out-of-spec.