Hello,
This is another update on my attempt on DMA-mapping framework redesign.
I focused mainly on the IOMMU mapper for ARM DMA-mapping implementation.
DMA-mapping patches have been rebased onto Linux v3.1-rc9-next kernel
with CMA v16 patches already applied. I've also integrated the code
provided by Krishna Reddy and added the missing methods for IOMMU DMA
mapper. The code has been tested on Samsung Exynos4 board.
Here is the link to the initial version of the DMA-mapping redesign patches:
http://www.spinics.net/lists/linux-mm/msg21241.html
Second version of the patches:
http://lists.linaro.org/pipermail/linaro-mm-sig/2011-September/000571.htmlhttp://lists.linaro.org/pipermail/linaro-mm-sig/2011-September/000577.html
TODO:
- start the discussion about chaning alloc_coherent into alloc_attrs in
dma_map_ops structure.
GIT tree will all the patches:
http://git.infradead.org/users/kmpark/linux-2.6-samsung/shortlog/refs/heads…git://git.infradead.org/users/kmpark/linux-2.6-samsung dma-mapping-v4
Best regards
--
Marek Szyprowski
Samsung Poland R&D Center
Patch summary:
Marek Szyprowski (8):
ARM: dma-mapping: remove offset parameter to prepare for generic
dma_ops
ARM: dma-mapping: use asm-generic/dma-mapping-common.h
ARM: dma-mapping: implement dma sg methods on top of any generic dma
ops
ARM: dma-mapping: move all dma bounce code to separate dma ops
structure
ARM: dma-mapping: remove redundant code and cleanup
common: dma-mapping: change alloc/free_coherent method to more
generic alloc/free_attrs
ARM: dma-mapping: use alloc, mmap, free from dma_ops
ARM: dma-mapping: add support for IOMMU mapper
arch/arm/Kconfig | 9 +
arch/arm/common/dmabounce.c | 78 +++-
arch/arm/include/asm/device.h | 5 +
arch/arm/include/asm/dma-iommu.h | 35 ++
arch/arm/include/asm/dma-mapping.h | 403 +++++------------
arch/arm/mm/dma-mapping.c | 869 +++++++++++++++++++++++++++++++-----
arch/arm/mm/vmregion.h | 2 +-
include/linux/dma-attrs.h | 1 +
include/linux/dma-mapping.h | 13 +-
9 files changed, 973 insertions(+), 442 deletions(-)
create mode 100644 arch/arm/include/asm/dma-iommu.h
--
1.7.1.569.g6f426
Hello Everyone,
Various subsystems - V4L2, GPU-accessors, DRI to name a few - have felt the
need to have a common mechanism to share memory buffers across different
devices - ARM, video hardware, GPU.
This need comes forth from a variety of use cases including cameras, image
processing, video recorders, sound processing, DMA engines, GPU and display
buffers, and others.
This RFC is the first attempt in defining such a buffer sharing mechanism- it is
the result of discussions from a couple of memory-management mini-summits held
by Linaro to understand and address common needs around memory management. [1]
A new dma_buf buffer object is added, with operations and API to allow easy
sharing of this buffer object across devices.
The framework allows:
- a new buffer-object to be created with fixed size.
- different devices to 'attach' themselves to this buffer, to facilitate
backing storage negotiation, using dma_buf_attach() API.
- association of a file pointer with each user-buffer and associated
allocator-defined operations on that buffer. This operation is called the
'export' operation.
- this exported buffer-object to be shared with the other entity by asking for
its 'file-descriptor (fd)', and sharing the fd across.
- a received fd to get the buffer object back, where it can be accessed using
the associated exporter-defined operations.
- the exporter and user to share the scatterlist using get_scatterlist and
put_scatterlist operations.
Documentation present in the patch-set gives more details.
This is based on design suggestions from many people at the mini-summits,
most notably from Arnd Bergmann <arnd(a)arndb.de>, Rob Clark <rob(a)ti.com> and
Daniel Vetter <daniel(a)ffwll.ch>.
The implementation is inspired from proof-of-concept patch-set from
Tomasz Stanislawski <t.stanislaws(a)samsung.com>, who demonstrated buffer sharing
between two v4l2 devices. [2]
References:
[1]: https://wiki.linaro.org/OfficeofCTO/MemoryManagement
[2]: http://lwn.net/Articles/454389
Sumit Semwal (2):
dma-buf: Introduce dma buffer sharing mechanism
dma-buf: Documentation for buffer sharing framework
Documentation/dma-buf-sharing.txt | 210 ++++++++++++++++++++++++++++++++
drivers/base/Kconfig | 10 ++
drivers/base/Makefile | 1 +
drivers/base/dma-buf.c | 242 +++++++++++++++++++++++++++++++++++++
include/linux/dma-buf.h | 162 +++++++++++++++++++++++++
5 files changed, 625 insertions(+), 0 deletions(-)
create mode 100644 Documentation/dma-buf-sharing.txt
create mode 100644 drivers/base/dma-buf.c
create mode 100644 include/linux/dma-buf.h
--
1.7.4.1
