linux-stable.git/Documentation/DMA-API.txt, branch v3.16.67

Documentation: DMA API: fix a typo in a function name

2017-10-12T14:27:44+00:00

commit 6a08d83e4324fcb23994dfd481acedf49e37cc06 upstream.

Correct the typo, the wrongly typed function does not exist.

Fixes: 6c9c6d6301287e ("dma-debug: New interfaces to debug dma mapping errors")
Signed-off-by: Wolfram Sang 
Signed-off-by: Jonathan Corbet 
Signed-off-by: Ben Hutchings

DMA-API: Capitalize "CPU" consistently

2014-05-26T23:28:27+00:00

Sometimes we used "cpu," other times "CPU."  Use "CPU" consistently.

Suggested-by: Randy Dunlap 
Signed-off-by: Bjorn Helgaas

DMA-API: Change dma_declare_coherent_memory() CPU address to phys_addr_t

2014-05-20T22:55:23+00:00

dma_declare_coherent_memory() takes two addresses for a region of memory: a
"bus_addr" and a "device_addr".  I think the intent is that "bus_addr" is
the physical address a *CPU* would use to access the region, and
"device_addr" is the bus address the *device* would use to address the
region.

Rename "bus_addr" to "phys_addr" and change its type to phys_addr_t.
Most callers already supply a phys_addr_t for this argument.  The others
supply a 32-bit integer (a constant, unsigned int, or __u32) and need no
change.

Use "unsigned long", not phys_addr_t, to hold PFNs.

No functional change (this could theoretically fix a truncation in a config
with 32-bit dma_addr_t and 64-bit phys_addr_t, but I don't think there are
any such cases involving this code).

Signed-off-by: Bjorn Helgaas 
Acked-by: Arnd Bergmann 
Acked-by: Greg Kroah-Hartman 
Acked-by: James Bottomley 
Acked-by: Randy Dunlap

DMA-API: Clarify physical/bus address distinction

2014-05-20T22:54:21+00:00

The DMA-API documentation sometimes refers to "physical addresses" when it
really means "bus addresses."  Sometimes these are identical, but they may
be different if the bridge leading to the bus performs address translation.
Update the documentation to use "bus address" when appropriate.

Also, consistently capitalize "DMA", use parens with function names, use
dev_printk() in examples, and reword a few sections for clarity.

No functional change; documentation changes only.

Signed-off-by: Bjorn Helgaas 
Acked-by: Greg Kroah-Hartman 
Acked-by: Arnd Bergmann 
Acked-by: James Bottomley 
Acked-by: Randy Dunlap

DMA-API: provide a helper to set both DMA and coherent DMA masks

2013-09-17T14:32:37+00:00

Provide a helper to set both the DMA and coherent DMA masks to the
same value - this avoids duplicated code in a number of drivers,
sometimes with buggy error handling, and also allows us identify
which drivers do things differently.

Signed-off-by: Russell King

dma-debug: New interfaces to debug dma mapping errors

2012-10-24T15:06:43+00:00

Add dma-debug interface debug_dma_mapping_error() to debug
drivers that fail to check dma mapping errors on addresses
returned by dma_map_single() and dma_map_page() interfaces.
This interface clears a flag set by debug_dma_map_page() to
indicate that dma_mapping_error() has been called by the
driver. When driver does unmap, debug_dma_unmap() checks the
flag and if this flag is still set, prints warning message
that includes call trace that leads up to the unmap. This
interface can be called from dma_mapping_error() routines to
enable dma mapping error check debugging.

Tested: Intel iommu and swiotlb (iommu=soft) on x86-64 with
        CONFIG_DMA_API_DEBUG enabled and disabled.

Signed-off-by: Shuah Khan 
Reviewed-by: Konrad Rzeszutek Wilk 
Signed-off-by: Joerg Roedel

include/linux/dma-mapping.h: add dma_zalloc_coherent()

2011-11-02T23:07:02+00:00

Lots of driver code does a dma_alloc_coherent() and then zeroes out the
memory with a memset.  Make it easy for them.

Cc: Alexandre Bounine 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

dma-mapping: remove dma_is_consistent API

2010-08-11T15:59:21+00:00

Architectures implement dma_is_consistent() in different ways (some
misinterpret the definition of API in DMA-API.txt).  So it hasn't been so
useful for drivers.  We have only one user of the API in tree.  Unlikely
out-of-tree drivers use the API.

Even if we fix dma_is_consistent() in some architectures, it doesn't look
useful at all.  It was invented long ago for some old systems that can't
allocate coherent memory at all.  It's better to export only APIs that are
definitely necessary for drivers.

Let's remove this API.

Signed-off-by: FUJITA Tomonori 
Cc: James Bottomley 
Reviewed-by: Konrad Rzeszutek Wilk 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Documentation: rename PCI-DMA-mapping.txt to DMA-API-HOWTO.txt

2010-03-12T23:52:43+00:00

Signed-off-by: FUJITA Tomonori 
Cc: James Bottomley 
Cc: "David S. Miller" 
Cc: Randy Dunlap 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Documentation: remove the PCI DMA API description in DMA-API.txt

2010-03-12T23:52:43+00:00

- remove the PCI DMA API description in DMA-API.txt
- remove the descriptions of dma_unmap macros since
  PCI-DMA-mapping.txt has the same description.

Signed-off-by: FUJITA Tomonori 
Cc: James Bottomley 
Cc: "David S. Miller" 
Reviewed-by: Randy Dunlap 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds