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authorLinus Torvalds <torvalds@linux-foundation.org>2019-05-09 08:40:55 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2019-05-09 08:40:55 -0700
commitddab5337b23c99777d7cfb39c0f8efe536c17dff (patch)
treefa2f935815614b474aca2e43afcddca69bda07fb /Documentation/DMA-API-HOWTO.txt
parente57ccca1ba33e1d92cc3bbf8b6304a46948844b0 (diff)
parent13bf5ced93775ffccb53527a9d862e023a9daa03 (diff)
Merge tag 'dma-mapping-5.2' of git://git.infradead.org/users/hch/dma-mapping
Pull DMA mapping updates from Christoph Hellwig: - remove the already broken support for NULL dev arguments to the DMA API calls - Kconfig tidyups * tag 'dma-mapping-5.2' of git://git.infradead.org/users/hch/dma-mapping: dma-mapping: add a Kconfig symbol to indicate arch_dma_prep_coherent presence dma-mapping: remove an unnecessary NULL check x86/dma: Remove the x86_dma_fallback_dev hack dma-mapping: remove leftover NULL device support arm: use a dummy struct device for ISA DMA use of the DMA API pxa3xx-gcu: pass struct device to dma_mmap_coherent gbefb: switch to managed version of the DMA allocator da8xx-fb: pass struct device to DMA API functions parport_ip32: pass struct device to DMA API functions dma: select GENERIC_ALLOCATOR for DMA_REMAP
Diffstat (limited to 'Documentation/DMA-API-HOWTO.txt')
-rw-r--r--Documentation/DMA-API-HOWTO.txt13
1 files changed, 6 insertions, 7 deletions
diff --git a/Documentation/DMA-API-HOWTO.txt b/Documentation/DMA-API-HOWTO.txt
index db48c6fd3162..cb712a02f59f 100644
--- a/Documentation/DMA-API-HOWTO.txt
+++ b/Documentation/DMA-API-HOWTO.txt
@@ -365,13 +365,12 @@ __get_free_pages() (but takes size instead of a page order). If your
driver needs regions sized smaller than a page, you may prefer using
the dma_pool interface, described below.
-The consistent DMA mapping interfaces, for non-NULL dev, will by
-default return a DMA address which is 32-bit addressable. Even if the
-device indicates (via DMA mask) that it may address the upper 32-bits,
-consistent allocation will only return > 32-bit addresses for DMA if
-the consistent DMA mask has been explicitly changed via
-dma_set_coherent_mask(). This is true of the dma_pool interface as
-well.
+The consistent DMA mapping interfaces, will by default return a DMA address
+which is 32-bit addressable. Even if the device indicates (via the DMA mask)
+that it may address the upper 32-bits, consistent allocation will only
+return > 32-bit addresses for DMA if the consistent DMA mask has been
+explicitly changed via dma_set_coherent_mask(). This is true of the
+dma_pool interface as well.
dma_alloc_coherent() returns two values: the virtual address which you
can use to access it from the CPU and dma_handle which you pass to the