[RFC PATCH 00/12] Ion cleanup in preparation for moving out of staging

Laurent Pinchart
2017-03-03T16:25:40Z

Hi Laura,

Thank you for the patches.

On Thursday 02 Mar 2017 13:44:32 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.

That's where most of my concerns with ion are. I still strongly believe that
the heap-based approach is inherently flawed, as it would need to be
configured for each device according to product-specific use cases. That's not
something that could be easily shipped with a generic distribution. We should
replace that with a constraint-based system.

> - 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.
>
> 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

--
Regards,

Laurent Pinchart