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_DMA_COHERENT_TO_PFN
57 config ARCH_HAS_FORCE_DMA_UNENCRYPTED
60 config DMA_NONCOHERENT_CACHE_SYNC
69 select NEED_DMA_MAP_STATE
73 select GENERIC_ALLOCATOR
76 config DMA_DIRECT_REMAP
81 bool "DMA Contiguous Memory Allocator"
82 depends on HAVE_DMA_CONTIGUOUS && CMA
84 This enables the Contiguous Memory Allocator which allows drivers
85 to allocate big physically-contiguous blocks of memory for use with
86 hardware components that do not support I/O map nor scatter-gather.
88 You can disable CMA by specifying "cma=0" on the kernel's command
91 For more information see <include/linux/dma-contiguous.h>.
95 comment "Default contiguous memory area size:"
97 config CMA_SIZE_MBYTES
98 int "Size in Mega Bytes"
99 depends on !CMA_SIZE_SEL_PERCENTAGE
103 Defines the size (in MiB) of the default memory area for Contiguous
104 Memory Allocator. If the size of 0 is selected, CMA is disabled by
105 default, but it can be enabled by passing cma=size[MG] to the kernel.
108 config CMA_SIZE_PERCENTAGE
109 int "Percentage of total memory"
110 depends on !CMA_SIZE_SEL_MBYTES
114 Defines the size of the default memory area for Contiguous Memory
115 Allocator as a percentage of the total memory in the system.
116 If 0 percent is selected, CMA is disabled by default, but it can be
117 enabled by passing cma=size[MG] to the kernel.
120 prompt "Selected region size"
121 default CMA_SIZE_SEL_MBYTES
123 config CMA_SIZE_SEL_MBYTES
124 bool "Use mega bytes value only"
126 config CMA_SIZE_SEL_PERCENTAGE
127 bool "Use percentage value only"
129 config CMA_SIZE_SEL_MIN
130 bool "Use lower value (minimum)"
132 config CMA_SIZE_SEL_MAX
133 bool "Use higher value (maximum)"
138 int "Maximum PAGE_SIZE order of alignment for contiguous buffers"
142 DMA mapping framework by default aligns all buffers to the smallest
143 PAGE_SIZE order which is greater than or equal to the requested buffer
144 size. This works well for buffers up to a few hundreds kilobytes, but
145 for larger buffers it just a memory waste. With this parameter you can
146 specify the maximum PAGE_SIZE order for contiguous buffers. Larger
147 buffers will be aligned only to this specified order. The order is
148 expressed as a power of two multiplied by the PAGE_SIZE.
150 For example, if your system defaults to 4KiB pages, the order value
151 of 8 means that the buffers will be aligned up to 1MiB only.
153 If unsure, leave the default value "8".
158 bool "Enable debugging of DMA-API usage"
159 select NEED_DMA_MAP_STATE
161 Enable this option to debug the use of the DMA API by device drivers.
162 With this option you will be able to detect common bugs in device
163 drivers like double-freeing of DMA mappings or freeing mappings that
164 were never allocated.
166 This also attempts to catch cases where a page owned by DMA is
167 accessed by the cpu in a way that could cause data corruption. For
168 example, this enables cow_user_page() to check that the source page is
171 This option causes a performance degradation. Use only if you want to
172 debug device drivers and dma interactions.
176 config DMA_API_DEBUG_SG
177 bool "Debug DMA scatter-gather usage"
179 depends on DMA_API_DEBUG
181 Perform extra checking that callers of dma_map_sg() have respected the
182 appropriate segment length/boundary limits for the given device when
183 preparing DMA scatterlists.
185 This is particularly likely to have been overlooked in cases where the
186 dma_map_sg() API is used for general bulk mapping of pages rather than
187 preparing literal scatter-gather descriptors, where there is a risk of
188 unexpected behaviour from DMA API implementations if the scatterlist
189 is technically out-of-spec.