arm64/imx9: Add DMA memory allocator #12228
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xiaoxiang781216
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Apr 24, 2024
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@xiaoxiang781216 is there some way to fix it: |
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Add a simple allocator for DMA safe memory. It will provide contiguous blocks of memory with D-Cache line size alignment. NOTE: The optimal granule size is the D-Cache line size (64), but due to restrictions in the granule allocator this would result in a maximum block size of 2K only, thus use 256B granules instead givin 8K max block size. Once the granule allocator is fixed this limitation can be removed.
Using user allocated buffers for DMA transfers is not safe for two reasons: - User space memory is virtual memory, DMA needs physical memory - User memory buffer alignment cannot be guaranteed -> cache line ops are not safe
xiaoxiang781216
approved these changes
Apr 30, 2024
jerpelea
approved these changes
Apr 30, 2024
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Summary
Add a DMA memory allocator for iMX9. Can be used for FAT sector buffers, peripheral DMA buffers and so forth. Separate, properly aligned buffers are needed for cache line alignment.
Impact
Add cache safe DMA buffers
Testing
imx93-evk:nsh