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_PREP_COHERENT
44 config ARCH_HAS_DMA_COHERENT_TO_PFN
47 config ARCH_HAS_DMA_MMAP_PGPROT
50 config DMA_NONCOHERENT_CACHE_SYNC
59 select NEED_DMA_MAP_STATE
63 select GENERIC_ALLOCATOR
66 config DMA_DIRECT_REMAP
71 bool "DMA Contiguous Memory Allocator"
72 depends on HAVE_DMA_CONTIGUOUS && CMA
74 This enables the Contiguous Memory Allocator which allows drivers
75 to allocate big physically-contiguous blocks of memory for use with
76 hardware components that do not support I/O map nor scatter-gather.
78 You can disable CMA by specifying "cma=0" on the kernel's command
81 For more information see <include/linux/dma-contiguous.h>.
85 comment "Default contiguous memory area size:"
87 config CMA_SIZE_MBYTES
88 int "Size in Mega Bytes"
89 depends on !CMA_SIZE_SEL_PERCENTAGE
93 Defines the size (in MiB) of the default memory area for Contiguous
94 Memory Allocator. If the size of 0 is selected, CMA is disabled by
95 default, but it can be enabled by passing cma=size[MG] to the kernel.
98 config CMA_SIZE_PERCENTAGE
99 int "Percentage of total memory"
100 depends on !CMA_SIZE_SEL_MBYTES
104 Defines the size of the default memory area for Contiguous Memory
105 Allocator as a percentage of the total memory in the system.
106 If 0 percent is selected, CMA is disabled by default, but it can be
107 enabled by passing cma=size[MG] to the kernel.
110 prompt "Selected region size"
111 default CMA_SIZE_SEL_MBYTES
113 config CMA_SIZE_SEL_MBYTES
114 bool "Use mega bytes value only"
116 config CMA_SIZE_SEL_PERCENTAGE
117 bool "Use percentage value only"
119 config CMA_SIZE_SEL_MIN
120 bool "Use lower value (minimum)"
122 config CMA_SIZE_SEL_MAX
123 bool "Use higher value (maximum)"
128 int "Maximum PAGE_SIZE order of alignment for contiguous buffers"
132 DMA mapping framework by default aligns all buffers to the smallest
133 PAGE_SIZE order which is greater than or equal to the requested buffer
134 size. This works well for buffers up to a few hundreds kilobytes, but
135 for larger buffers it just a memory waste. With this parameter you can
136 specify the maximum PAGE_SIZE order for contiguous buffers. Larger
137 buffers will be aligned only to this specified order. The order is
138 expressed as a power of two multiplied by the PAGE_SIZE.
140 For example, if your system defaults to 4KiB pages, the order value
141 of 8 means that the buffers will be aligned up to 1MiB only.
143 If unsure, leave the default value "8".
148 bool "Enable debugging of DMA-API usage"
149 select NEED_DMA_MAP_STATE
151 Enable this option to debug the use of the DMA API by device drivers.
152 With this option you will be able to detect common bugs in device
153 drivers like double-freeing of DMA mappings or freeing mappings that
154 were never allocated.
156 This also attempts to catch cases where a page owned by DMA is
157 accessed by the cpu in a way that could cause data corruption. For
158 example, this enables cow_user_page() to check that the source page is
161 This option causes a performance degradation. Use only if you want to
162 debug device drivers and dma interactions.
166 config DMA_API_DEBUG_SG
167 bool "Debug DMA scatter-gather usage"
169 depends on DMA_API_DEBUG
171 Perform extra checking that callers of dma_map_sg() have respected the
172 appropriate segment length/boundary limits for the given device when
173 preparing DMA scatterlists.
175 This is particularly likely to have been overlooked in cases where the
176 dma_map_sg() API is used for general bulk mapping of pages rather than
177 preparing literal scatter-gather descriptors, where there is a risk of
178 unexpected behaviour from DMA API implementations if the scatterlist
179 is technically out-of-spec.