Re: [RESEND][PATCH v8 0/5] DMA-BUF Heaps (destaging ION)

[Andrew F. Davis]

On 10/9/19 1:37 PM, Ayan Halder wrote:
> On Tue, Sep 24, 2019 at 04:22:18PM +0000, Ayan Halder wrote:
>> On Thu, Sep 19, 2019 at 10:21:52PM +0530, Sumit Semwal wrote:
>>> Hello Christoph, everyone,
>>>
>>> On Sat, 7 Sep 2019 at 00:17, John Stultz <john.stultz@xxxxxxxxxx> wrote:
>>>>
>>>> Here is yet 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, since any such accounting
>>>> should be implemented by dma-buf core or the heaps themselves.
>>>>
>>>> Most of the changes in this revision are adddressing the more
>>>> concrete feedback from Christoph (many thanks!). Though I'm not
>>>> sure if some of the less specific feedback was completely resolved
>>>> in discussion last time around. Please let me know!
>>>
>>> It looks like most of the feedback has been taken care of. If there's
>>> no more objection to this series, I'd like to merge it in soon.
>>>
>>> If there are any more review comments, may I request you to please provide them?
>>
>> I tested these patches using our internal test suite with Arm,komeda
>> driver and the following node in dts
>>
>>         reserved-memory {
>>                 #address-cells = <0x2>;
>>                 #size-cells = <0x2>;
>>                 ranges;
>>
>>                 framebuffer@60000000 {
>>                         compatible = "shared-dma-pool";
>>                         linux,cma-default;
>>                         reg = <0x0 0x60000000 0x0 0x8000000>;
>>                 };
>>         }
> Apologies for the confusion, this dts node is irrelevant as our tests were using
> the cma heap (via /dev/dma_heap/reserved).
> 
> That raises a question. How do we represent the reserved-memory nodes
> (as shown above) via the dma-buf heaps framework ?


The CMA driver that registers these nodes will have to be expanded to
export them using this framework as needed. We do something similar to
export SRAM nodes:

https://lkml.org/lkml/2019/3/21/575

Unlike the system/default-cma driver which can be centralized in the
tree, these extra exporters will probably live out in other subsystems
and so are added in later steps.

Andrew


>>
>> The tests went fine. Our tests allocates framebuffers of different
>> sizes, posts them on screen and the driver writes back to one of the
>> framebuffers. I havenot tested for any performance, latency or
>> cache management related stuff. So, it that looks appropriate, feel
>> free to add:-
>> Tested-by:- Ayan Kumar Halder <ayan.halder@xxxxxxx>
>>
>> Are you planning to write some igt tests for it ?
>>>
>>>>
>>>> New in v8:
>>>> * Make struct dma_heap_ops consts (Suggested by Christoph)
>>>> * Add flush_kernel_vmap_range/invalidate_kernel_vmap_range calls
>>>>   (suggested by Christoph)
>>>> * Condense dma_heap_buffer and heap_helper_buffer (suggested by
>>>>   Christoph)
>>>> * Get rid of needless struct system_heap (suggested by Christoph)
>>>> * Fix indentation by using shorter argument names (suggested by
>>>>   Christoph)
>>>> * Remove unused private_flags value
>>>> * Add forgotten include file to fix build issue on x86
>>>> * Checkpatch whitespace fixups
>>>>
>>>> Thoughts and feedback would be greatly appreciated!
>>>>
>>>> thanks
>>>> -john
>>> Best,
>>> Sumit.
>>>>
>>>> Cc: Laura Abbott <labbott@xxxxxxxxxx>
>>>> Cc: Benjamin Gaignard <benjamin.gaignard@xxxxxxxxxx>
>>>> Cc: Sumit Semwal <sumit.semwal@xxxxxxxxxx>
>>>> Cc: Liam Mark <lmark@xxxxxxxxxxxxxx>
>>>> Cc: Pratik Patel <pratikp@xxxxxxxxxxxxxx>
>>>> Cc: Brian Starkey <Brian.Starkey@xxxxxxx>
>>>> Cc: Vincent Donnefort <Vincent.Donnefort@xxxxxxx>
>>>> Cc: Sudipto Paul <Sudipto.Paul@xxxxxxx>
>>>> Cc: Andrew F. Davis <afd@xxxxxx>
>>>> Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
>>>> Cc: Chenbo Feng <fengc@xxxxxxxxxx>
>>>> Cc: Alistair Strachan <astrachan@xxxxxxxxxx>
>>>> Cc: Hridya Valsaraju <hridya@xxxxxxxxxx>
>>>> Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
>>>>
>>>>
>>>> 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                       |  11 +
>>>>  drivers/dma-buf/Makefile                      |   2 +
>>>>  drivers/dma-buf/dma-heap.c                    | 250 ++++++++++++++++
>>>>  drivers/dma-buf/heaps/Kconfig                 |  14 +
>>>>  drivers/dma-buf/heaps/Makefile                |   4 +
>>>>  drivers/dma-buf/heaps/cma_heap.c              | 164 +++++++++++
>>>>  drivers/dma-buf/heaps/heap-helpers.c          | 269 ++++++++++++++++++
>>>>  drivers/dma-buf/heaps/heap-helpers.h          |  55 ++++
>>>>  drivers/dma-buf/heaps/system_heap.c           | 122 ++++++++
>>>>  include/linux/dma-heap.h                      |  59 ++++
>>>>  include/uapi/linux/dma-heap.h                 |  55 ++++
>>>>  tools/testing/selftests/dmabuf-heaps/Makefile |   9 +
>>>>  .../selftests/dmabuf-heaps/dmabuf-heap.c      | 230 +++++++++++++++
>>>>  14 files changed, 1262 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
>>>>
>>>
>>>
>>> -- 
>>> Thanks and regards,
>>>
>>> Sumit Semwal
>>> Linaro Consumer Group - Kernel Team Lead
>>> Linaro.org â Open source software for ARM SoCs
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