Hi Daniel,
On 2017-10-17 14:24, Daniel Vetter wrote:
On Tue, Oct 17, 2017 at 01:07:43PM +0200, Marek Szyprowski wrote:
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, Exynos5422
Odroid XU3 and Exynos5433 TM2 boards, on top of Linux next-20171016 kernel.
When submitting uapi changes, please link to the corresponding userspace
work. Otherwise pretty hard to find this stuff.
A simple userspace test tool has been sent together with v1:
https://www.spinics.net/lists/linux-samsung-soc/msg60498.html
Tobias Jakobi has added support for this new API to his fork of libdrm and
mpv video player:
https://github.com/tobiasjakobi/libdrm/tree/ippv2
https://github.com/tobiasjakobi/mpv
Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland
_______________________________________________
dri-devel mailing list
dri-devel@xxxxxxxxxxxxxxxxxxxxx
https://lists.freedesktop.org/mailman/listinfo/dri-devel
