MIPS: Add implementation of dma_map_ops.mmap()

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The generic implementation of dma_map_ops.mmap(), dma_common_mmap(),
is not correct for non-coherent devices. It expects to be passed a
virtual address previously returned by dma_alloc_coherent(), which for
a non-coherent device will return a KSEG1 address. It then attempts to
convert that virtual address to a physical address using virt_to_page()
which will yield an incorrect address.

Also, dma_common_mmap() does not handle the DMA_ATTR_WRITE_COMBINE
attribute, and therefore dma_mmap_writecombine() will not actually set
the appropriate pgprot_t flags for write combining.

This patch adds an implementation of dma_map_ops.mmap() that correctly
handles KSEG1 addresses, and enables write combining when requested.

Signed-off-by: Alex Smith <alex.smith@imgtec.com>
Cc: Sadegh Abbasi <Sadegh.Abbasi@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/10808/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

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Alex Smith 2015-07-30 12:03:42 +01:00 • committed by Ralf Baechle

parent c4687b15a8

commit 8c172467be

1 changed files with 35 additions and 0 deletions

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arch/mips/mm/dma-default.c

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