diff options
author | Krzysztof Kozlowski <k.kozlowski@samsung.com> | 2016-08-03 13:46:00 -0700 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-08-04 08:50:07 -0400 |
commit | 00085f1efa387a8ce100e3734920f7639c80caa3 (patch) | |
tree | 41ff3d6e6884918b4fc4f1ae96a284098167c5b0 /Documentation | |
parent | 1605d2715ad2e67ddd0485a26e05ed670a4285ca (diff) | |
download | linux-stable-00085f1efa387a8ce100e3734920f7639c80caa3.tar.gz linux-stable-00085f1efa387a8ce100e3734920f7639c80caa3.tar.bz2 linux-stable-00085f1efa387a8ce100e3734920f7639c80caa3.zip |
dma-mapping: use unsigned long for dma_attrs
The dma-mapping core and the implementations do not change the DMA
attributes passed by pointer. Thus the pointer can point to const data.
However the attributes do not have to be a bitfield. Instead unsigned
long will do fine:
1. This is just simpler. Both in terms of reading the code and setting
attributes. Instead of initializing local attributes on the stack
and passing pointer to it to dma_set_attr(), just set the bits.
2. It brings safeness and checking for const correctness because the
attributes are passed by value.
Semantic patches for this change (at least most of them):
virtual patch
virtual context
@r@
identifier f, attrs;
@@
f(...,
- struct dma_attrs *attrs
+ unsigned long attrs
, ...)
{
...
}
@@
identifier r.f;
@@
f(...,
- NULL
+ 0
)
and
// Options: --all-includes
virtual patch
virtual context
@r@
identifier f, attrs;
type t;
@@
t f(..., struct dma_attrs *attrs);
@@
identifier r.f;
@@
f(...,
- NULL
+ 0
)
Link: http://lkml.kernel.org/r/1468399300-5399-2-git-send-email-k.kozlowski@samsung.com
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Acked-by: Vineet Gupta <vgupta@synopsys.com>
Acked-by: Robin Murphy <robin.murphy@arm.com>
Acked-by: Hans-Christian Noren Egtvedt <egtvedt@samfundet.no>
Acked-by: Mark Salter <msalter@redhat.com> [c6x]
Acked-by: Jesper Nilsson <jesper.nilsson@axis.com> [cris]
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> [drm]
Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>
Acked-by: Joerg Roedel <jroedel@suse.de> [iommu]
Acked-by: Fabien Dessenne <fabien.dessenne@st.com> [bdisp]
Reviewed-by: Marek Szyprowski <m.szyprowski@samsung.com> [vb2-core]
Acked-by: David Vrabel <david.vrabel@citrix.com> [xen]
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> [xen swiotlb]
Acked-by: Joerg Roedel <jroedel@suse.de> [iommu]
Acked-by: Richard Kuo <rkuo@codeaurora.org> [hexagon]
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> [m68k]
Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [s390]
Acked-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Acked-by: Hans-Christian Noren Egtvedt <egtvedt@samfundet.no> [avr32]
Acked-by: Vineet Gupta <vgupta@synopsys.com> [arc]
Acked-by: Robin Murphy <robin.murphy@arm.com> [arm64 and dma-iommu]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/DMA-API.txt | 33 | ||||
-rw-r--r-- | Documentation/DMA-attributes.txt | 2 |
2 files changed, 15 insertions, 20 deletions
diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt index 45ef3f279c3b..1d26eeb6b5f6 100644 --- a/Documentation/DMA-API.txt +++ b/Documentation/DMA-API.txt @@ -369,35 +369,32 @@ See also dma_map_single(). dma_addr_t dma_map_single_attrs(struct device *dev, void *cpu_addr, size_t size, enum dma_data_direction dir, - struct dma_attrs *attrs) + unsigned long attrs) void dma_unmap_single_attrs(struct device *dev, dma_addr_t dma_addr, size_t size, enum dma_data_direction dir, - struct dma_attrs *attrs) + unsigned long attrs) int dma_map_sg_attrs(struct device *dev, struct scatterlist *sgl, int nents, enum dma_data_direction dir, - struct dma_attrs *attrs) + unsigned long attrs) void dma_unmap_sg_attrs(struct device *dev, struct scatterlist *sgl, int nents, enum dma_data_direction dir, - struct dma_attrs *attrs) + unsigned long attrs) The four functions above are just like the counterpart functions without the _attrs suffixes, except that they pass an optional -struct dma_attrs*. - -struct dma_attrs encapsulates a set of "DMA attributes". For the -definition of struct dma_attrs see linux/dma-attrs.h. +dma_attrs. The interpretation of DMA attributes is architecture-specific, and each attribute should be documented in Documentation/DMA-attributes.txt. -If struct dma_attrs* is NULL, the semantics of each of these -functions is identical to those of the corresponding function +If dma_attrs are 0, the semantics of each of these functions +is identical to those of the corresponding function without the _attrs suffix. As a result dma_map_single_attrs() can generally replace dma_map_single(), etc. @@ -405,15 +402,15 @@ As an example of the use of the *_attrs functions, here's how you could pass an attribute DMA_ATTR_FOO when mapping memory for DMA: -#include <linux/dma-attrs.h> -/* DMA_ATTR_FOO should be defined in linux/dma-attrs.h and +#include <linux/dma-mapping.h> +/* DMA_ATTR_FOO should be defined in linux/dma-mapping.h and * documented in Documentation/DMA-attributes.txt */ ... - DEFINE_DMA_ATTRS(attrs); - dma_set_attr(DMA_ATTR_FOO, &attrs); + unsigned long attr; + attr |= DMA_ATTR_FOO; .... - n = dma_map_sg_attrs(dev, sg, nents, DMA_TO_DEVICE, &attr); + n = dma_map_sg_attrs(dev, sg, nents, DMA_TO_DEVICE, attr); .... Architectures that care about DMA_ATTR_FOO would check for its @@ -422,12 +419,10 @@ routines, e.g.: void whizco_dma_map_sg_attrs(struct device *dev, dma_addr_t dma_addr, size_t size, enum dma_data_direction dir, - struct dma_attrs *attrs) + unsigned long attrs) { .... - int foo = dma_get_attr(DMA_ATTR_FOO, attrs); - .... - if (foo) + if (attrs & DMA_ATTR_FOO) /* twizzle the frobnozzle */ .... diff --git a/Documentation/DMA-attributes.txt b/Documentation/DMA-attributes.txt index e8cf9cf873b3..2d455a5cf671 100644 --- a/Documentation/DMA-attributes.txt +++ b/Documentation/DMA-attributes.txt @@ -2,7 +2,7 @@ ============== This document describes the semantics of the DMA attributes that are -defined in linux/dma-attrs.h. +defined in linux/dma-mapping.h. DMA_ATTR_WRITE_BARRIER ---------------------- |