[PATCH 0/6] Exynos DRM: rewrite IPP subsystem and userspace API

[Tobias Jakobi]

Hey Marek,

first of all thanks for keeping this series alive. Looks pretty good so far.

I have started to rewrite my IPP userspace API in libdrm and when this is done,
I'm going to adapt my mpv video backend to it.

With best wishes,
Tobias



Marek Szyprowski wrote:
> Dear all,
> 
> This patchset performs complete rewrite of Exynos DRM IPP subsystem and
> its userspace API.
> 
> Why such rewrite is needed? Exynos DRM IPP API is over-engineered in
> general, but not really extensible on the other side. It is also buggy,
> with significant design flaws:
> - Userspace API covers memory-2-memory picture operations together with
>   CRTC writeback and duplicating features, which belongs to video plane.
> - Lack of support of the all required image formats (for example NV12
>   Samsung-tiled cannot be used due to lack of pixel format modifier
>   support).
> - Userspace API designed only to mimic hardware behaviour, not easy to
>   understand.
> - Lack of proper input validation in the core, drivers also didn't do that
>   correctly, so it was possible to set incorrect parameters and easil
>   trigger IOMMU fault or memory trash.
> - Drivers were partially disfunctional or supported only a subset of modes.
> 
> Due to the above limitations and issues the Exynos DRM IPP API was not
> used by any of the open-source projects. I assume that it is safe to remove
> this broken API without any damage to open-source community. All remaining
> users (mainly Tizen project related) will be updated to the new version.
> 
> This patchset changes Exynos DRM IPP subsystem to something useful. The
> userspace API is much simpler, state-less and easy to understand. Also
> the code of the core and driver is significantly smaller and easier to
> understand.
> 
> Patches were tested on Exynos4412 based Odroid U3 and Exynos5422
> Odroid XU3 boards, on top of Linux next-20170911 kernel.
> 
> Best regards
> Marek Szyprowski
> Samsung R&D Institute Poland
> 
> 
> My previous works in this area:
> 
> "[RFC v2 0/2] Exynos DRM: add Picture Processor extension"
> https://www.spinics.net/lists/dri-devel/msg140669.html
> - removed usage of DRM objects and properties - replaced them with simple
>   list of parameters with predefined IDs
> 
> "[RFC 0/4] Exynos DRM: add Picture Processor extension"
> https://www.spinics.net/lists/linux-samsung-soc/msg59323.html
> - moved this feature from DRM core to Exynos DRM driver
> - changed name from framebuffer processor to picture processor
> - simplified code to cover only things needed by Exynos drivers
> - implemented simple fifo task scheduler
> - cleaned up rotator driver conversion (removed IPP remainings)
> 
> "[RFC 0/2] New feature: Framebuffer processors"
> https://www.spinics.net/lists/linux-samsung-soc/msg54810.html
> - generic approach implemented in DRM core, rejected
> 
> 
> Patch summary:
> 
> Marek Szyprowski (6):
>   drm/exynos: ipp: Remove Exynos DRM IPP subsystem
>   drm/exynos: ipp: Add IPP v2 framework
>   drm/exynos: rotator: Convert driver to IPP v2 core API
>   drm/exynos: gsc: Convert driver to IPP v2 core API
>   drm/exynos: Add generic support for devices shared with V4L2 subsystem
>   drm/exynos: fimc: Convert driver to IPP v2 core API
> 
>  drivers/gpu/drm/exynos/Kconfig              |   12 +-
>  drivers/gpu/drm/exynos/exynos_drm_drv.c     |   33 +-
>  drivers/gpu/drm/exynos/exynos_drm_drv.h     |    4 +-
>  drivers/gpu/drm/exynos/exynos_drm_fimc.c    |  893 +++--------
>  drivers/gpu/drm/exynos/exynos_drm_fimc.h    |   23 -
>  drivers/gpu/drm/exynos/exynos_drm_gsc.c     |  853 +++-------
>  drivers/gpu/drm/exynos/exynos_drm_gsc.h     |   24 -
>  drivers/gpu/drm/exynos/exynos_drm_ipp.c     | 2239 ++++++++-------------------
>  drivers/gpu/drm/exynos/exynos_drm_ipp.h     |  352 ++---
>  drivers/gpu/drm/exynos/exynos_drm_rotator.c |  735 ++-------
>  drivers/gpu/drm/exynos/exynos_drm_rotator.h |   19 -
>  include/uapi/drm/exynos_drm.h               |  315 ++--
>  12 files changed, 1627 insertions(+), 3875 deletions(-)
>  delete mode 100644 drivers/gpu/drm/exynos/exynos_drm_fimc.h
>  delete mode 100644 drivers/gpu/drm/exynos/exynos_drm_gsc.h
>  delete mode 100644 drivers/gpu/drm/exynos/exynos_drm_rotator.h
>