The Video Engine present on all (?) AllWinner SoCs includes a JPEG decoder, which shares the same engine as the MPEG2 decoder. I mostly used the linux-sunxi resources on the engine[0], as well as some reverse-engineered userland using the legacy /dev/cedar_dev API[1]. I wrote the Onix library[2] to exercise this driver. With it, I have tested this series on the A10, A20 and A64, as found in Olimex Lime, Lime 2 and PinePhone respectively, so further testing on other SoCs would be very welcome. On the A10 and A20, since only the tiled ST12 format is supported, the file dump binary is a bit unusable, but I have tested displaying to DRM and to Wayland just fine on these SoCs. They also only support downscaling from 4:4:4 to 4:2:2, unlike newer SoCs which support downscaling from either 4:4:4 or 4:2:2 to 4:2:2 or 4:2:0. This prompts the issue of which formats to advertise: currently I chose to only expose NV12, but ideally NV16 would be exposed when the user tries to decode a 4:2:2 or 4:4:4 image. By the time the user has called ENUM_FMTS on the capture queue, the driver doesn’t know the subsampling in the JPEG file, so it can’t expose only the supported formats. A possible solution could be to add a new v4l2_ext_ctrl describing the JPEG, but this is a new uAPI which should get discussed outside of this driver. [0] https://linux-sunxi.org/VE_Register_guide [1] https://github.com/jemk/cedrus [2] https://linkmauve.fr/dev/onix/ Emmanuel Gil Peyrot (1): media: cedrus: Add JPEG decoder Jernej Skrabec (3): media: cedrus: Setup secondary output formats media: cedrus: Enable JPEG decoding in various variants media: cedrus: Don't require requests for all codecs drivers/staging/media/sunxi/cedrus/Kconfig | 1 + drivers/staging/media/sunxi/cedrus/Makefile | 2 +- drivers/staging/media/sunxi/cedrus/cedrus.c | 10 + drivers/staging/media/sunxi/cedrus/cedrus.h | 5 + .../staging/media/sunxi/cedrus/cedrus_hw.c | 14 +- .../staging/media/sunxi/cedrus/cedrus_jpeg.c | 352 ++++++++++++++++++ .../staging/media/sunxi/cedrus/cedrus_regs.h | 25 +- .../staging/media/sunxi/cedrus/cedrus_video.c | 11 +- 8 files changed, 413 insertions(+), 7 deletions(-) create mode 100644 drivers/staging/media/sunxi/cedrus/cedrus_jpeg.c -- 2.45.2
