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
24 # Select this option if the architecture needs special handling for
25 # DMA_ATTR_WRITE_COMBINE. Normally the "uncached" mapping should be what
26 # people thing of when saying write combine, so very few platforms should
27 # need to enable this.
29 config ARCH_HAS_DMA_WRITE_COMBINE
32 config DMA_DECLARE_COHERENT
35 config ARCH_HAS_SETUP_DMA_OPS
38 config ARCH_HAS_TEARDOWN_DMA_OPS
41 config ARCH_HAS_SYNC_DMA_FOR_DEVICE
44 config ARCH_HAS_SYNC_DMA_FOR_CPU
46 select NEED_DMA_MAP_STATE
48 config ARCH_HAS_SYNC_DMA_FOR_CPU_ALL
51 config ARCH_HAS_DMA_PREP_COHERENT
54 config ARCH_HAS_FORCE_DMA_UNENCRYPTED
57 config DMA_NONCOHERENT_CACHE_SYNC
66 select NEED_DMA_MAP_STATE
69 # Should be selected if we can mmap non-coherent mappings to userspace.
70 # The only thing that is really required is a way to set an uncached bit
73 config DMA_NONCOHERENT_MMAP
78 select GENERIC_ALLOCATOR
79 select DMA_NONCOHERENT_MMAP
82 config DMA_DIRECT_REMAP
87 bool "DMA Contiguous Memory Allocator"
88 depends on HAVE_DMA_CONTIGUOUS && CMA
90 This enables the Contiguous Memory Allocator which allows drivers
91 to allocate big physically-contiguous blocks of memory for use with
92 hardware components that do not support I/O map nor scatter-gather.
94 You can disable CMA by specifying "cma=0" on the kernel's command
97 For more information see <include/linux/dma-contiguous.h>.
101 comment "Default contiguous memory area size:"
103 config CMA_SIZE_MBYTES
104 int "Size in Mega Bytes"
105 depends on !CMA_SIZE_SEL_PERCENTAGE
109 Defines the size (in MiB) of the default memory area for Contiguous
110 Memory Allocator. If the size of 0 is selected, CMA is disabled by
111 default, but it can be enabled by passing cma=size[MG] to the kernel.
114 config CMA_SIZE_PERCENTAGE
115 int "Percentage of total memory"
116 depends on !CMA_SIZE_SEL_MBYTES
120 Defines the size of the default memory area for Contiguous Memory
121 Allocator as a percentage of the total memory in the system.
122 If 0 percent is selected, CMA is disabled by default, but it can be
123 enabled by passing cma=size[MG] to the kernel.
126 prompt "Selected region size"
127 default CMA_SIZE_SEL_MBYTES
129 config CMA_SIZE_SEL_MBYTES
130 bool "Use mega bytes value only"
132 config CMA_SIZE_SEL_PERCENTAGE
133 bool "Use percentage value only"
135 config CMA_SIZE_SEL_MIN
136 bool "Use lower value (minimum)"
138 config CMA_SIZE_SEL_MAX
139 bool "Use higher value (maximum)"
144 int "Maximum PAGE_SIZE order of alignment for contiguous buffers"
148 DMA mapping framework by default aligns all buffers to the smallest
149 PAGE_SIZE order which is greater than or equal to the requested buffer
150 size. This works well for buffers up to a few hundreds kilobytes, but
151 for larger buffers it just a memory waste. With this parameter you can
152 specify the maximum PAGE_SIZE order for contiguous buffers. Larger
153 buffers will be aligned only to this specified order. The order is
154 expressed as a power of two multiplied by the PAGE_SIZE.
156 For example, if your system defaults to 4KiB pages, the order value
157 of 8 means that the buffers will be aligned up to 1MiB only.
159 If unsure, leave the default value "8".
164 bool "Enable debugging of DMA-API usage"
165 select NEED_DMA_MAP_STATE
167 Enable this option to debug the use of the DMA API by device drivers.
168 With this option you will be able to detect common bugs in device
169 drivers like double-freeing of DMA mappings or freeing mappings that
170 were never allocated.
172 This also attempts to catch cases where a page owned by DMA is
173 accessed by the cpu in a way that could cause data corruption. For
174 example, this enables cow_user_page() to check that the source page is
177 This option causes a performance degradation. Use only if you want to
178 debug device drivers and dma interactions.
182 config DMA_API_DEBUG_SG
183 bool "Debug DMA scatter-gather usage"
185 depends on DMA_API_DEBUG
187 Perform extra checking that callers of dma_map_sg() have respected the
188 appropriate segment length/boundary limits for the given device when
189 preparing DMA scatterlists.
191 This is particularly likely to have been overlooked in cases where the
192 dma_map_sg() API is used for general bulk mapping of pages rather than
193 preparing literal scatter-gather descriptors, where there is a risk of
194 unexpected behaviour from DMA API implementations if the scatterlist
195 is technically out-of-spec.