Date:   Fri, 3 Mar 2017 13:54:07 +0100
From:   Benjamin Gaignard <benjamin.gaignard@...aro.org>
To:     Laura Abbott <labbott@...hat.com>,
        Sumit Semwal <sumit.semwal@...aro.org>,
        Riley Andrews <riandrews@...roid.com>,
        Arve Hjønnevåg <arve@...roid.com>,
        romlem@...gle.com, devel@...verdev.osuosl.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "linaro-mm-sig@...ts.linaro.org" <linaro-mm-sig@...ts.linaro.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-arm-kernel@...ts.infradead.org,
        "linux-media@...r.kernel.org" <linux-media@...r.kernel.org>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        Brian Starkey <brian.starkey@....com>,
        Daniel Vetter <daniel.vetter@...el.com>,
        Mark Brown <broonie@...nel.org>,
        Benjamin Gaignard <benjamin.gaignard@...aro.org>,
        linux-mm@...ck.org
Subject: Re: [RFC PATCH 00/12] Ion cleanup in preparation for moving out of staging

2017-03-03 11:27 GMT+01:00 Daniel Vetter <daniel@...ll.ch>:
> On Fri, Mar 03, 2017 at 11:04:33AM +0100, Daniel Vetter wrote:
>> On Thu, Mar 02, 2017 at 01:44:32PM -0800, Laura Abbott wrote:
>> > Hi,
>> >
>> > There's been some recent discussions[1] about Ion-like frameworks. There's
>> > apparently interest in just keeping Ion since it works reasonablly well.
>> > This series does what should be the final clean ups for it to possibly be
>> > moved out of staging.
>> >
>> > This includes the following:
>> > - Some general clean up and removal of features that never got a lot of use
>> >   as far as I can tell.
>> > - Fixing up the caching. This is the series I proposed back in December[2]
>> >   but never heard any feedback on. It will certainly break existing
>> >   applications that rely on the implicit caching. I'd rather make an effort
>> >   to move to a model that isn't going directly against the establishement
>> >   though.
>> > - Fixing up the platform support. The devicetree approach was never well
>> >   recieved by DT maintainers. The proposal here is to think of Ion less as
>> >   specifying requirements and more of a framework for exposing memory to
>> >   userspace.
>> > - CMA allocations now happen without the need of a dummy device structure.
>> >   This fixes a bunch of the reasons why I attempted to add devicetree
>> >   support before.
>> >
>> > I've had problems getting feedback in the past so if I don't hear any major
>> > objections I'm going to send out with the RFC dropped to be picked up.
>> > The only reason there isn't a patch to come out of staging is to discuss any
>> > other changes to the ABI people might want. Once this comes out of staging,
>> > I really don't want to mess with the ABI.
>> >
>> > Feedback appreciated.
>>
>> Imo looks all good. And I just realized that cross-checking with the TODO,
>> the 2 items about _CUSTOM and _IMPORT ioctls I noted are already there.
>
> One more for the todo: Add rst/sphinx documentation for ION. That's also
> always a good excuse to review the internal interfaces and exported
> symbols. But we can do that after destaging ...
> -Daniel

Removing alignment looks good for me but why not also remove it from
struct ion_allocation_data since the field become useless ?

Also does someone use ion_user_handle_t handle ? Can we directly export
a dma-buf file descriptor ?

Benjamin

>
>>
>> Otherwise I looked through the patches, looks all really reasonable.
>>
>> Wrt merging, my experience from destaging the android syncpt stuff was
>> that merging the patches through the staging tree lead to lots of
>> cross-tree issues with the gpu folks wanting to use that. Ion will
>> probably run into similar things, so I'd propose we pull these cleanup
>> patches and the eventual de-staging in throught drm. Yes that defacto
>> means I'm also volunteering myself a bit :-)
>>
>> In the end we could put it all into drivers/gpu/ion or something like
>> that.
>>
>> Thoughts? Greg?
>> -Daniel
>>
>>
>> >
>> > Thanks,
>> > Laura
>> >
>> > [1] https://marc.info/?l=linux-kernel&m=148699712602105&w=2
>> > [2] https://marc.info/?l=linaro-mm-sig&m=148176050802908&w=2
>> >
>> > Laura Abbott (12):
>> >   staging: android: ion: Remove dmap_cnt
>> >   staging: android: ion: Remove alignment from allocation field
>> >   staging: android: ion: Duplicate sg_table
>> >   staging: android: ion: Call dma_map_sg for syncing and mapping
>> >   staging: android: ion: Remove page faulting support
>> >   staging: android: ion: Remove crufty cache support
>> >   staging: android: ion: Remove old platform support
>> >   cma: Store a name in the cma structure
>> >   cma: Introduce cma_for_each_area
>> >   staging: android: ion: Use CMA APIs directly
>> >   staging: android: ion: Make Ion heaps selectable
>> >   staging; android: ion: Enumerate all available heaps
>> >
>> >  drivers/base/dma-contiguous.c                      |   5 +-
>> >  drivers/staging/android/ion/Kconfig                |  51 ++--
>> >  drivers/staging/android/ion/Makefile               |  14 +-
>> >  drivers/staging/android/ion/hisilicon/Kconfig      |   5 -
>> >  drivers/staging/android/ion/hisilicon/Makefile     |   1 -
>> >  drivers/staging/android/ion/hisilicon/hi6220_ion.c | 113 ---------
>> >  drivers/staging/android/ion/ion-ioctl.c            |   6 -
>> >  drivers/staging/android/ion/ion.c                  | 282 ++++++---------------
>> >  drivers/staging/android/ion/ion.h                  |   5 +-
>> >  drivers/staging/android/ion/ion_carveout_heap.c    |  16 +-
>> >  drivers/staging/android/ion/ion_chunk_heap.c       |  15 +-
>> >  drivers/staging/android/ion/ion_cma_heap.c         | 102 ++------
>> >  drivers/staging/android/ion/ion_dummy_driver.c     | 156 ------------
>> >  drivers/staging/android/ion/ion_enumerate.c        |  89 +++++++
>> >  drivers/staging/android/ion/ion_of.c               | 184 --------------
>> >  drivers/staging/android/ion/ion_of.h               |  37 ---
>> >  drivers/staging/android/ion/ion_page_pool.c        |   3 -
>> >  drivers/staging/android/ion/ion_priv.h             |  57 ++++-
>> >  drivers/staging/android/ion/ion_system_heap.c      |  14 +-
>> >  drivers/staging/android/ion/tegra/Makefile         |   1 -
>> >  drivers/staging/android/ion/tegra/tegra_ion.c      |  80 ------
>> >  include/linux/cma.h                                |   6 +-
>> >  mm/cma.c                                           |  25 +-
>> >  mm/cma.h                                           |   1 +
>> >  mm/cma_debug.c                                     |   2 +-
>> >  25 files changed, 312 insertions(+), 958 deletions(-)
>> >  delete mode 100644 drivers/staging/android/ion/hisilicon/Kconfig
>> >  delete mode 100644 drivers/staging/android/ion/hisilicon/Makefile
>> >  delete mode 100644 drivers/staging/android/ion/hisilicon/hi6220_ion.c
>> >  delete mode 100644 drivers/staging/android/ion/ion_dummy_driver.c
>> >  create mode 100644 drivers/staging/android/ion/ion_enumerate.c
>> >  delete mode 100644 drivers/staging/android/ion/ion_of.c
>> >  delete mode 100644 drivers/staging/android/ion/ion_of.h
>> >  delete mode 100644 drivers/staging/android/ion/tegra/Makefile
>> >  delete mode 100644 drivers/staging/android/ion/tegra/tegra_ion.c
>> >
>> > --
>> > 2.7.4
>> >
>> > --
>> > To unsubscribe, send a message with 'unsubscribe linux-mm' in
>> > the body to majordomo@...ck.org.  For more info on Linux MM,
>> > see: http://www.linux-mm.org/ .
>> > Don't email: <a href=mailto:"dont@...ck.org"> email@...ck.org </a>
>>
>> --
>> Daniel Vetter
>> Software Engineer, Intel Corporation
>> http://blog.ffwll.ch
>
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch

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