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Subject[RFC][PATCH 0/5 v4] DMA-BUF Heaps (destaging ION)
Here is another RFC of the dma-buf heaps patchset Andrew and I
have been working on which tries to destage a fair chunk of ION

The patchset implements per-heap devices which can be opened
directly and then an ioctl is used to allocate a dmabuf from the

The interface is similar, but much simpler then IONs, only
providing an ALLOC ioctl.

Also, I've provided relatively simple system and cma heaps.

I've booted and tested these patches with AOSP on the HiKey960
using the kernel tree here:

And the userspace changes here:

Compared to ION, this patchset is missing the system-contig,
carveout and chunk heaps, as I don't have a device that uses
those, so I'm unable to do much useful validation there.
Additionally we have no upstream users of chunk or carveout,
and the system-contig has been deprecated in the common/andoid-*
kernels, so this should be ok.

I've also removed the stats accounting for now, since any such
accounting should be implemented by dma-buf core or the heaps

New in v4:
* Add fd_flags per Benjamin's request to specify the creation
flags for the dmabuf fd.
* Added some optimization in the system heap to allocate
contiguous pages where possible.
* Reworked the kselftest code to use vgem rather then
introducing a dummy importer
* Other cleanups suggested by Benjamin and Andrew.

Outstanding concerns:
* Need to better understand various secure heap implementations.
Some concern that heap private flags will be needed, but its
also possible that dma-buf heaps can't solve everyone's needs,
in which case, a vendor's secure buffer driver can implement
their own dma-buf exporter.
* Making sure the performance issues from potentially
unnecessary cache-management operations can be resolved
properly for system and cma heaps(outstanding issue from ION).

That said, the main user-interface is shaping up and I wanted
to get some input on the device model (particularly from GreKH)
and any other API/ABI specific input.


Cc: Laura Abbott <>
Cc: Benjamin Gaignard <>
Cc: Sumit Semwal <>
Cc: Liam Mark <>
Cc: Pratik Patel <>
Cc: Brian Starkey <>
Cc: Vincent Donnefort <>
Cc: Sudipto Paul <>
Cc: Andrew F. Davis <>
Cc: Xu YiPing <>
Cc: "Chenfeng (puck)" <>
Cc: butao <>
Cc: "Xiaqing (A)" <>
Cc: Yudongbin <>
Cc: Christoph Hellwig <>
Cc: Chenbo Feng <>
Cc: Alistair Strachan <>

Andrew F. Davis (1):
dma-buf: Add dma-buf heaps framework

John Stultz (4):
dma-buf: heaps: Add heap helpers
dma-buf: heaps: Add system heap to dmabuf heaps
dma-buf: heaps: Add CMA heap to dmabuf heaps
kselftests: Add dma-heap test

drivers/dma-buf/Kconfig | 10 +
drivers/dma-buf/Makefile | 2 +
drivers/dma-buf/dma-heap.c | 241 ++++++++++++++++
drivers/dma-buf/heaps/Kconfig | 14 +
drivers/dma-buf/heaps/Makefile | 4 +
drivers/dma-buf/heaps/cma_heap.c | 169 ++++++++++++
drivers/dma-buf/heaps/heap-helpers.c | 261 ++++++++++++++++++
drivers/dma-buf/heaps/heap-helpers.h | 55 ++++
drivers/dma-buf/heaps/system_heap.c | 162 +++++++++++
include/linux/dma-heap.h | 59 ++++
include/uapi/linux/dma-heap.h | 56 ++++
tools/testing/selftests/dmabuf-heaps/Makefile | 11 +
.../selftests/dmabuf-heaps/dmabuf-heap.c | 232 ++++++++++++++++
14 files changed, 1294 insertions(+)
create mode 100644 drivers/dma-buf/dma-heap.c
create mode 100644 drivers/dma-buf/heaps/Kconfig
create mode 100644 drivers/dma-buf/heaps/Makefile
create mode 100644 drivers/dma-buf/heaps/cma_heap.c
create mode 100644 drivers/dma-buf/heaps/heap-helpers.c
create mode 100644 drivers/dma-buf/heaps/heap-helpers.h
create mode 100644 drivers/dma-buf/heaps/system_heap.c
create mode 100644 include/linux/dma-heap.h
create mode 100644 include/uapi/linux/dma-heap.h
create mode 100644 tools/testing/selftests/dmabuf-heaps/Makefile
create mode 100644 tools/testing/selftests/dmabuf-heaps/dmabuf-heap.c


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