Hi everyone, This patch ports the VP9 library written by Andrzej into Rust as a proof-of-concept. This is so that we can evaluate the Rust in V4L2 initiative with source code in hand. It converts rkvdec and hantro to use the Rust version of the library. These two were chosen merely because that's the hardware I currently own. Fluster scores remain the same when using either the Rust or C version. Please test this. Much has been spoken at various occasions about drivers and I feel that the consensus is to wait for now. This is why I am proposing a different approach: porting our codec libraries to Rust. IMHO, these components can benefit greatly from Rust, as they implement complicated algorithms that also happen to process data received from userspace through V4L2 controls. These algorithms use the data received from userspace in order to index into a lot of arrays and thus benefit from Rust's memory safety. The first thing about the code is that it does not include any layer of bindings. This was pointed out as a blocker several times due to the need of keeping them in sync with the C code. The Rust code here also offers a C API for C drivers.This C API is automatically generated by cbindgen and I have provided instructions on how to do so. We can even use functions from both the C and Rust libraries at the same time since the ABI is the same. The above can come in handy because it means that we can convert a given codebase piece by piece if need be. C drivers will work as usual through the C API and any new Rust driver will get to benefit from a native Rust interface. Please take note that most of the code is *not* in the media tree, so I do not see how this can further stress our subsystem. I take responsibility for maintaining stuff in rust/kernel/media and honestly, this library will not need any further updates for the same reason we have never touched its C counterpart. I hope to convince the community that this is a feasible way to slowly experiment with Rust code without tying us up too much to it. Lastly, please note that this code is just a proof of concept, we can settle on a proper patch - with all that entails - if it is well received. Those with hardware can follow the steps below to test this patch: a) enable Rust (https://www.kernel.org/doc/html/latest/rust/quick-start.html). Make sure CONFIG_RUST=y. b) enable one of the converted drivers (CONFIG_VIDEO_HANTRO or CONFIG_VIDEO_ROCKCHIP_VDEC). This will select V4L2_VP9_RS. c) download the Fluster tool (https://github.com/fluendo/fluster) d) download the VP9 test suite from libvpx (fluster.py download VP9-TEST-VECTORS) e) make sure you have a recent version of GStreamer (`gst-inspect-1.0 v4l2codecs` must not be empty) f) run the test suite (fluster.py run -d GStreamer-VP9-V4L2SL-Gst1.0 -ts VP9-TEST-VECTORS) g) results should be the same both with and without this patch -- Daniel Applies on top of: commit d9c1fae3e5b225f2e45e0bca519f9a2967cd1062 Author: Alice Ryhl <aliceryhl@xxxxxxxxxx> Date: Fri Feb 9 11:18:22 2024 +0000 rust: file: add abstraction for `poll_table` For those looking for a branch instead: https://gitlab.collabora.com/dwlsalmeida/for-upstream/-/tree/vp9-rs?ref_type=heads Daniel Almeida (1): v4l2-core: rewrite the VP9 library in Rust drivers/media/platform/verisilicon/Kconfig | 2 +- .../platform/verisilicon/hantro_g2_vp9_dec.c | 38 +- .../media/platform/verisilicon/hantro_hw.h | 8 +- drivers/media/v4l2-core/Kconfig | 4 + drivers/staging/media/rkvdec/Kconfig | 2 +- drivers/staging/media/rkvdec/rkvdec-vp9.c | 52 +- include/media/v4l2-vp9-rs.h | 97 + rust/bindings/bindings_helper.h | 1 + rust/kernel/lib.rs | 2 + rust/kernel/media.rs | 5 + rust/kernel/media/v4l2_core.rs | 6 + rust/kernel/media/v4l2_core/cbindgen.toml | 26 + rust/kernel/media/v4l2_core/vp9.rs | 1999 +++++++++++++++++ 13 files changed, 2192 insertions(+), 50 deletions(-) create mode 100644 include/media/v4l2-vp9-rs.h create mode 100644 rust/kernel/media.rs create mode 100644 rust/kernel/media/v4l2_core.rs create mode 100644 rust/kernel/media/v4l2_core/cbindgen.toml create mode 100644 rust/kernel/media/v4l2_core/vp9.rs -- 2.43.0
