1 # SPDX-License-Identifier: GPL-2.0-only
8 config NEED_SG_DMA_LENGTH
11 config NEED_DMA_MAP_STATE
14 config ARCH_DMA_ADDR_T_64BIT
15 def_bool 64BIT || PHYS_ADDR_T_64BIT
17 config ARCH_HAS_DMA_COHERENCE_H
20 config ARCH_HAS_DMA_SET_MASK
23 config DMA_DECLARE_COHERENT
26 config ARCH_HAS_SETUP_DMA_OPS
29 config ARCH_HAS_TEARDOWN_DMA_OPS
32 config ARCH_HAS_SYNC_DMA_FOR_DEVICE
35 config ARCH_HAS_SYNC_DMA_FOR_CPU
37 select NEED_DMA_MAP_STATE
39 config ARCH_HAS_SYNC_DMA_FOR_CPU_ALL
42 config ARCH_HAS_DMA_PREP_COHERENT
45 config ARCH_HAS_DMA_COHERENT_TO_PFN
48 config ARCH_HAS_DMA_MMAP_PGPROT
51 config DMA_NONCOHERENT_CACHE_SYNC
60 select NEED_DMA_MAP_STATE
64 select GENERIC_ALLOCATOR
67 config DMA_DIRECT_REMAP
72 bool "DMA Contiguous Memory Allocator"
73 depends on HAVE_DMA_CONTIGUOUS && CMA
75 This enables the Contiguous Memory Allocator which allows drivers
76 to allocate big physically-contiguous blocks of memory for use with
77 hardware components that do not support I/O map nor scatter-gather.
79 You can disable CMA by specifying "cma=0" on the kernel's command
82 For more information see <include/linux/dma-contiguous.h>.
86 comment "Default contiguous memory area size:"
88 config CMA_SIZE_MBYTES
89 int "Size in Mega Bytes"
90 depends on !CMA_SIZE_SEL_PERCENTAGE
94 Defines the size (in MiB) of the default memory area for Contiguous
95 Memory Allocator. If the size of 0 is selected, CMA is disabled by
96 default, but it can be enabled by passing cma=size[MG] to the kernel.
99 config CMA_SIZE_PERCENTAGE
100 int "Percentage of total memory"
101 depends on !CMA_SIZE_SEL_MBYTES
105 Defines the size of the default memory area for Contiguous Memory
106 Allocator as a percentage of the total memory in the system.
107 If 0 percent is selected, CMA is disabled by default, but it can be
108 enabled by passing cma=size[MG] to the kernel.
111 prompt "Selected region size"
112 default CMA_SIZE_SEL_MBYTES
114 config CMA_SIZE_SEL_MBYTES
115 bool "Use mega bytes value only"
117 config CMA_SIZE_SEL_PERCENTAGE
118 bool "Use percentage value only"
120 config CMA_SIZE_SEL_MIN
121 bool "Use lower value (minimum)"
123 config CMA_SIZE_SEL_MAX
124 bool "Use higher value (maximum)"
129 int "Maximum PAGE_SIZE order of alignment for contiguous buffers"
133 DMA mapping framework by default aligns all buffers to the smallest
134 PAGE_SIZE order which is greater than or equal to the requested buffer
135 size. This works well for buffers up to a few hundreds kilobytes, but
136 for larger buffers it just a memory waste. With this parameter you can
137 specify the maximum PAGE_SIZE order for contiguous buffers. Larger
138 buffers will be aligned only to this specified order. The order is
139 expressed as a power of two multiplied by the PAGE_SIZE.
141 For example, if your system defaults to 4KiB pages, the order value
142 of 8 means that the buffers will be aligned up to 1MiB only.
144 If unsure, leave the default value "8".
149 bool "Enable debugging of DMA-API usage"
150 select NEED_DMA_MAP_STATE
152 Enable this option to debug the use of the DMA API by device drivers.
153 With this option you will be able to detect common bugs in device
154 drivers like double-freeing of DMA mappings or freeing mappings that
155 were never allocated.
157 This also attempts to catch cases where a page owned by DMA is
158 accessed by the cpu in a way that could cause data corruption. For
159 example, this enables cow_user_page() to check that the source page is
162 This option causes a performance degradation. Use only if you want to
163 debug device drivers and dma interactions.
167 config DMA_API_DEBUG_SG
168 bool "Debug DMA scatter-gather usage"
170 depends on DMA_API_DEBUG
172 Perform extra checking that callers of dma_map_sg() have respected the
173 appropriate segment length/boundary limits for the given device when
174 preparing DMA scatterlists.
176 This is particularly likely to have been overlooked in cases where the
177 dma_map_sg() API is used for general bulk mapping of pages rather than
178 preparing literal scatter-gather descriptors, where there is a risk of
179 unexpected behaviour from DMA API implementations if the scatterlist
180 is technically out-of-spec.