[RFC][PATCH 0/6 v3] DMA-BUF Heaps (destaging ION)

[John Stultz]

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
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 simple system and cma heaps. The system
heap in particular is missing the page-pool optimizations ION
had, but works well enough to validate the interface.

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 it should
be implemented by the heaps themselves.


New in v3:
* Proper /dev/heap/* names on both Android and classic Linux
  environments
* Major rework of the helper code from Andrew
* Dummy test device added to test importing
* *Lots* of cleanups suggested by many (thank you for all the
  input)!


Outstanding concerns:
* Potential need for private flags in interface for secure
  heaps. Need to better understand secure heap usage.
* Making sure the performance issues from potentially unnecessary
  cache-management operations can be resolved properly for system
  and cma heaps (outstanding issue from ION).


Eventual TODOS:
* Sanity filtering for heap names
* Reimplement performance optimizations for system heap
* Add stats accounting to system/cma heaps
* Make the kselftest more useful
* Add other heaps folks see as useful (would love to get
  some help from actual carveout/chunk users)!

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. 

thanks
-john

Cc: Laura Abbott <labbott at redhat.com>
Cc: Benjamin Gaignard <benjamin.gaignard at linaro.org>
Cc: Sumit Semwal <sumit.semwal at linaro.org>
Cc: Liam Mark <lmark at codeaurora.org>
Cc: Pratik Patel <pratikp at codeaurora.org>
Cc: Brian Starkey <Brian.Starkey at arm.com>
Cc: Vincent Donnefort <Vincent.Donnefort at arm.com>
Cc: Sudipto Paul <Sudipto.Paul at arm.com>
Cc: Andrew F. Davis <afd at ti.com>
Cc: Xu YiPing <xuyiping at hisilicon.com>
Cc: "Chenfeng (puck)" <puck.chen at hisilicon.com>
Cc: butao <butao at hisilicon.com>
Cc: "Xiaqing (A)" <saberlily.xia at hisilicon.com>
Cc: Yudongbin <yudongbin at hisilicon.com>
Cc: Christoph Hellwig <hch at infradead.org>
Cc: Chenbo Feng <fengc at google.com>
Cc: Alistair Strachan <astrachan at google.com>
Cc: dri-devel at lists.freedesktop.org

Andrew F. Davis (2):
  dma-buf: Add dma-buf heaps framework
  dma-buf: Add Dummy Importer Test Device

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 heapss
  kselftests: Add dma-heap test

 MAINTAINERS                                        |  18 ++
 drivers/dma-buf/Kconfig                            |  16 ++
 drivers/dma-buf/Makefile                           |   3 +
 drivers/dma-buf/dma-buf-testdev.c                  | 239 +++++++++++++++++++
 drivers/dma-buf/dma-heap.c                         | 234 ++++++++++++++++++
 drivers/dma-buf/heaps/Kconfig                      |  14 ++
 drivers/dma-buf/heaps/Makefile                     |   4 +
 drivers/dma-buf/heaps/cma_heap.c                   | 170 ++++++++++++++
 drivers/dma-buf/heaps/heap-helpers.c               | 261 +++++++++++++++++++++
 drivers/dma-buf/heaps/heap-helpers.h               |  55 +++++
 drivers/dma-buf/heaps/system_heap.c                | 120 ++++++++++
 include/linux/dma-heap.h                           |  58 +++++
 include/uapi/linux/dma-buf-testdev.h               |  37 +++
 include/uapi/linux/dma-heap.h                      |  52 ++++
 tools/testing/selftests/dmabuf-heaps/Makefile      |  11 +
 tools/testing/selftests/dmabuf-heaps/dmabuf-heap.c | 169 +++++++++++++
 16 files changed, 1461 insertions(+)
 create mode 100644 drivers/dma-buf/dma-buf-testdev.c
 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-buf-testdev.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

-- 
2.7.4