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Subject[PATCH v5 0/5] DMA-BUF Heaps (destaging ION)
Date
Here is another pass at the dma-buf heaps patchset Andrew and I
have been working on which tries to destage a fair chunk of ION
functionality.

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

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:
https://git.linaro.org/people/john.stultz/android-dev.git/log/?h=dev/dma-buf-heap

And the userspace changes here:
https://android-review.googlesource.com/c/device/linaro/hikey/+/909436

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
themselves.


New in v5:
* Actually not much that I'm submitting now. I've backed out the
large order page allocation I added in v4 as using it with the
pagelist structure in the helper buffers ended up leaking
memory unless we split them, and then we didn't see any
performance improvement.
* I have spent a fair amount of time looking at allocation
performance compared to ION, and I do have a patch stack
that performs equal or better then ION (utilizing large order
allocations, sgtables, and a page pool). However, Andrew
convinced me that the extra complexity of these optimizations
would distract reviewers from the core functionality, and we
can submit those changes afterwards without any interface
impact. WIP patches can be found here:
https://git.linaro.org/people/john.stultz/android-dev.git/log/?h=dev/dma-buf-heap-WIP
* Minor cleanups


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. So I'm not too worried here.

Thoughts and feedback would be greatly appreciated!

thanks
-john


Cc: Laura Abbott <labbott@redhat.com>
Cc: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Liam Mark <lmark@codeaurora.org>
Cc: Pratik Patel <pratikp@codeaurora.org>
Cc: Brian Starkey <Brian.Starkey@arm.com>
Cc: Vincent Donnefort <Vincent.Donnefort@arm.com>
Cc: Sudipto Paul <Sudipto.Paul@arm.com>
Cc: Andrew F. Davis <afd@ti.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Chenbo Feng <fengc@google.com>
Cc: Alistair Strachan <astrachan@google.com>
Cc: dri-devel@lists.freedesktop.org


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

MAINTAINERS | 18 ++
drivers/dma-buf/Kconfig | 10 +
drivers/dma-buf/Makefile | 2 +
drivers/dma-buf/dma-heap.c | 237 ++++++++++++++++
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 | 123 +++++++++
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, 1251 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

--
2.17.1

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