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authorLinus Torvalds <torvalds@linux-foundation.org>2017-07-07 04:20:54 +0200
committerLinus Torvalds <torvalds@linux-foundation.org>2017-07-07 04:20:54 +0200
commitf72e24a1240b78f421649c4d88f5c24ab1c896a1 (patch)
tree90bed3bf33ae0abf5636dafcc3eda3cc354612b0 /Documentation
parentMerge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s39... (diff)
parentARM: dma-mapping: Remove traces of NOMMU code (diff)
downloadlinux-f72e24a1240b78f421649c4d88f5c24ab1c896a1.tar.xz
linux-f72e24a1240b78f421649c4d88f5c24ab1c896a1.zip
Merge tag 'dma-mapping-4.13' of git://git.infradead.org/users/hch/dma-mapping
Pull dma-mapping infrastructure from Christoph Hellwig: "This is the first pull request for the new dma-mapping subsystem In this new subsystem we'll try to properly maintain all the generic code related to dma-mapping, and will further consolidate arch code into common helpers. This pull request contains: - removal of the DMA_ERROR_CODE macro, replacing it with calls to ->mapping_error so that the dma_map_ops instances are more self contained and can be shared across architectures (me) - removal of the ->set_dma_mask method, which duplicates the ->dma_capable one in terms of functionality, but requires more duplicate code. - various updates for the coherent dma pool and related arm code (Vladimir) - various smaller cleanups (me)" * tag 'dma-mapping-4.13' of git://git.infradead.org/users/hch/dma-mapping: (56 commits) ARM: dma-mapping: Remove traces of NOMMU code ARM: NOMMU: Set ARM_DMA_MEM_BUFFERABLE for M-class cpus ARM: NOMMU: Introduce dma operations for noMMU drivers: dma-mapping: allow dma_common_mmap() for NOMMU drivers: dma-coherent: Introduce default DMA pool drivers: dma-coherent: Account dma_pfn_offset when used with device tree dma: Take into account dma_pfn_offset dma-mapping: replace dmam_alloc_noncoherent with dmam_alloc_attrs dma-mapping: remove dmam_free_noncoherent crypto: qat - avoid an uninitialized variable warning au1100fb: remove a bogus dma_free_nonconsistent call MAINTAINERS: add entry for dma mapping helpers powerpc: merge __dma_set_mask into dma_set_mask dma-mapping: remove the set_dma_mask method powerpc/cell: use the dma_supported method for ops switching powerpc/cell: clean up fixed mapping dma_ops initialization tile: remove dma_supported and mapping_error methods xen-swiotlb: remove xen_swiotlb_set_dma_mask arm: implement ->dma_supported instead of ->set_dma_mask mips/loongson64: implement ->dma_supported instead of ->set_dma_mask ...
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/DMA-API-HOWTO.txt31
-rw-r--r--Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt3
-rw-r--r--Documentation/driver-model/devres.txt3
3 files changed, 9 insertions, 28 deletions
diff --git a/Documentation/DMA-API-HOWTO.txt b/Documentation/DMA-API-HOWTO.txt
index 979228bc9035..4ed388356898 100644
--- a/Documentation/DMA-API-HOWTO.txt
+++ b/Documentation/DMA-API-HOWTO.txt
@@ -550,32 +550,11 @@ and to unmap it:
dma_unmap_single(dev, dma_handle, size, direction);
You should call dma_mapping_error() as dma_map_single() could fail and return
-error. Not all DMA implementations support the dma_mapping_error() interface.
-However, it is a good practice to call dma_mapping_error() interface, which
-will invoke the generic mapping error check interface. Doing so will ensure
-that the mapping code will work correctly on all DMA implementations without
-any dependency on the specifics of the underlying implementation. Using the
-returned address without checking for errors could result in failures ranging
-from panics to silent data corruption. A couple of examples of incorrect ways
-to check for errors that make assumptions about the underlying DMA
-implementation are as follows and these are applicable to dma_map_page() as
-well.
-
-Incorrect example 1:
- dma_addr_t dma_handle;
-
- dma_handle = dma_map_single(dev, addr, size, direction);
- if ((dma_handle & 0xffff != 0) || (dma_handle >= 0x1000000)) {
- goto map_error;
- }
-
-Incorrect example 2:
- dma_addr_t dma_handle;
-
- dma_handle = dma_map_single(dev, addr, size, direction);
- if (dma_handle == DMA_ERROR_CODE) {
- goto map_error;
- }
+error. Doing so will ensure that the mapping code will work correctly on all
+DMA implementations without any dependency on the specifics of the underlying
+implementation. Using the returned address without checking for errors could
+result in failures ranging from panics to silent data corruption. The same
+applies to dma_map_page() as well.
You should call dma_unmap_single() when the DMA activity is finished, e.g.,
from the interrupt which told you that the DMA transfer is done.
diff --git a/Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt b/Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt
index 3da0ebdba8d9..16291f2a4688 100644
--- a/Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt
+++ b/Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt
@@ -68,6 +68,9 @@ Linux implementation note:
- If a "linux,cma-default" property is present, then Linux will use the
region for the default pool of the contiguous memory allocator.
+- If a "linux,dma-default" property is present, then Linux will use the
+ region for the default pool of the consistent DMA allocator.
+
Device node references to reserved memory
-----------------------------------------
Regions in the /reserved-memory node may be referenced by other device
diff --git a/Documentation/driver-model/devres.txt b/Documentation/driver-model/devres.txt
index 2d132fcea0f8..4231b45b2f8f 100644
--- a/Documentation/driver-model/devres.txt
+++ b/Documentation/driver-model/devres.txt
@@ -240,10 +240,9 @@ CLOCK
DMA
dmam_alloc_coherent()
- dmam_alloc_noncoherent()
+ dmam_alloc_attrs()
dmam_declare_coherent_memory()
dmam_free_coherent()
- dmam_free_noncoherent()
dmam_pool_create()
dmam_pool_destroy()