Re: [PATCH v12 0/5] DMA-BUF Heaps (destaging ION)

[Sumit Semwal]

Hi John, Andrews,

On Fri, 18 Oct 2019 at 10:53, John Stultz <john.stultz@xxxxxxxxxx> wrote:
>
> Andrew brought up a reasonable concern with the CMA heap
> enumeration in the previous patch set, and I had a few other
> minor cleanups to add, so 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.

Thanks much for all your hardwork in getting these patches ready. It
looks like a sane approach to me to first just add the default cma
heap and work out the selection of other heaps later on.

I will wait out this weekend for any objections from others, and if I
hear none, will merge this series on Monday.
Hope that sounds reasonable?

>
> 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.
>
> New in v12:
> * To address Andrew's concern about adding all CMA areas, the
>   CMA heap only adds the default CMA region for now.
> * Minor cleanups and prep for loading heaps from modules
> * I have patches to add other specified CMA regions, as well as
>   loading heaps from modules in my WIP tree, which I will submit
>   once this set is queued, here:
>     https://git.linaro.org/people/john.stultz/android-dev.git/log/?h=dev/dma-buf-heap-WIP
>
> thanks
> -john

<snip>

Best,
Sumit.