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dma-mapping: remove the {alloc,free}_noncoherent methods

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It turns out allowing non-contigous allocations here was a rather bad
idea, as we'll now need to define ways to get the pages for mmaping
or dma_buf sharing.  Revert this change and stick to the original
concept.  A different API for the use case of non-contigous allocations
will be added back later.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Tomasz Figa <tfiga@chromium.org>
Tested-by: Ricardo Ribalda <ribalda@chromium.org>:wq
This commit is contained in:
Christoph Hellwig
2020-11-24 16:38:40 +01:00
parent 9dc00b25ea
commit 81d88ce550
5 changed files with 36 additions and 122 deletions
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66
Documentation/core-api/dma-api.rst
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@@ -526,46 +526,6 @@ for the kernel vs the device.
If you don't understand how cache line coherency works between a processor and
an I/O device, you should not be using this part of the API.
::
void *
dma_alloc_noncoherent(struct device *dev, size_t size,
dma_addr_t *dma_handle, enum dma_data_direction dir,
gfp_t gfp)
This routine allocates a region of <size> bytes of consistent memory. It
returns a pointer to the allocated region (in the processor's virtual address
space) or NULL if the allocation failed. The returned memory may or may not
be in the kernel direct mapping. Drivers must not call virt_to_page on
the returned memory region.
It also returns a <dma_handle> which may be cast to an unsigned integer the
same width as the bus and given to the device as the DMA address base of
the region.
The dir parameter specified if data is read and/or written by the device,
see dma_map_single() for details.
The gfp parameter allows the caller to specify the ``GFP_`` flags (see
kmalloc()) for the allocation, but rejects flags used to specify a memory
zone such as GFP_DMA or GFP_HIGHMEM.
Before giving the memory to the device, dma_sync_single_for_device() needs
to be called, and before reading memory written by the device,
dma_sync_single_for_cpu(), just like for streaming DMA mappings that are
reused.
::
void
dma_free_noncoherent(struct device *dev, size_t size, void *cpu_addr,
dma_addr_t dma_handle, enum dma_data_direction dir)
Free a region of memory previously allocated using dma_alloc_noncoherent().
dev, size and dma_handle and dir must all be the same as those passed into
dma_alloc_noncoherent(). cpu_addr must be the virtual address returned by
dma_alloc_noncoherent().
::
struct page *
@@ -600,9 +560,29 @@ reused.
dma_addr_t dma_handle, enum dma_data_direction dir)
Free a region of memory previously allocated using dma_alloc_pages().
dev, size and dma_handle and dir must all be the same as those passed into
dma_alloc_noncoherent(). page must be the pointer returned by
dma_alloc_pages().
dev, size, dma_handle and dir must all be the same as those passed into
dma_alloc_pages(). page must be the pointer returned by dma_alloc_pages().
::
void *
dma_alloc_noncoherent(struct device *dev, size_t size,
dma_addr_t *dma_handle, enum dma_data_direction dir,
gfp_t gfp)
This routine is a convenient wrapper around dma_alloc_pages that returns the
kernel virtual address for the allocated memory instead of the page structure.
::
void
dma_free_noncoherent(struct device *dev, size_t size, void *cpu_addr,
dma_addr_t dma_handle, enum dma_data_direction dir)
Free a region of memory previously allocated using dma_alloc_noncoherent().
dev, size, dma_handle and dir must all be the same as those passed into
dma_alloc_noncoherent(). cpu_addr must be the virtual address returned by
dma_alloc_noncoherent().
::