quoted

2.
345 ENTRY(v7_dma_unmap_area)
346         add     r1, r1, r0
347         teq     r2, #DMA_TO_DEVICE
348         bne     v7_dma_inv_range
349         mov     pc, lr
350 ENDPROC(v7_dma_unmap_area)

v7_dma_unmap_area, will invalidate corresponding cache line for
?DMA_FROM_DEVICE?. But, at v7_dma_map_area, the invalidate has been done.
Why do this again?

Cache prefetching.

Speculative prefetch?

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