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authorSumit Semwal <sumit.semwal@ti.com>2011-12-26 14:53:15 +0530
committerRohan Somvanshi <rsomvanshi@nvidia.com>2012-02-03 05:20:29 -0800
commit9ba7a60e8c71e46580da32f4d0e8eed3fb11a47a (patch)
treea28eeb20648edb1076a65fed8eeb2364ce1d052d /drivers/base/Makefile
parentc8bee9dfd45d9bc9e35cc735567f25a210e87a5c (diff)
dma-buf: Introduce dma buffer sharing mechanism
This is the first step in defining a dma buffer sharing mechanism. A new buffer object dma_buf is added, with operations and API to allow easy sharing of this buffer object across devices. The framework allows: - creation of a buffer object, its association with a file pointer, and associated allocator-defined operations on that buffer. This operation is called the 'export' operation. - different devices to 'attach' themselves to this exported buffer object, to facilitate backing storage negotiation, using dma_buf_attach() API. - the 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 associated with this buffer object using map_dma_buf and unmap_dma_buf operations. Atleast one 'attach()' call is required to be made prior to calling the map_dma_buf() operation. Couple of building blocks in map_dma_buf() are added to ease introduction of sync'ing across exporter and users, and late allocation by the exporter. For this first version, this framework will work with certain conditions: - *ONLY* exporter will be allowed to mmap to userspace (outside of this framework - mmap is not a buffer object operation), - currently, *ONLY* users that do not need CPU access to the buffer are allowed. More details are there in the documentation patch. This is based on design suggestions from many people at the mini-summits[1], most notably from Arnd Bergmann <arnd@arndb.de>, Rob Clark <rob@ti.com> and Daniel Vetter <daniel@ffwll.ch>. The implementation is inspired from proof-of-concept patch-set from Tomasz Stanislawski <t.stanislaws@samsung.com>, who demonstrated buffer sharing between two v4l2 devices. [2] [1]: https://wiki.linaro.org/OfficeofCTO/MemoryManagement [2]: http://lwn.net/Articles/454389 Change-Id: I8ebd858ad86242ee7b02d5f42bb25c3edbd64fca Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org> Signed-off-by: Sumit Semwal <sumit.semwal@ti.com> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Reviewed-by: Dave Airlie <airlied@redhat.com> Reviewed-and-Tested-by: Rob Clark <rob.clark@linaro.org> Signed-off-by: Dave Airlie <airlied@redhat.com> Signed-off-by: Hiroshi DOYU <hdoyu@nvidia.com> [Hiroshi DOYU: Backported from v3.3-rc1] Reviewed-on: http://git-master/r/78384 Reviewed-by: Automatic_Commit_Validation_User Reviewed-by: Varun Wadekar <vwadekar@nvidia.com> Reviewed-by: Ken Adams <kadams@nvidia.com>
Diffstat (limited to 'drivers/base/Makefile')
-rw-r--r--drivers/base/Makefile1
1 files changed, 1 insertions, 0 deletions
diff --git a/drivers/base/Makefile b/drivers/base/Makefile
index 99a375ad2cc9..d0df046a70d8 100644
--- a/drivers/base/Makefile
+++ b/drivers/base/Makefile
@@ -8,6 +8,7 @@ obj-$(CONFIG_DEVTMPFS) += devtmpfs.o
obj-y += power/
obj-$(CONFIG_HAS_DMA) += dma-mapping.o
obj-$(CONFIG_HAVE_GENERIC_DMA_COHERENT) += dma-coherent.o
+obj-$(CONFIG_DMA_SHARED_BUFFER) += dma-buf.o
obj-$(CONFIG_ISA) += isa.o
obj-$(CONFIG_FW_LOADER) += firmware_class.o
obj-$(CONFIG_NUMA) += node.o