[RFC 0/4] media: meson: add video decoder driver

Maxime Jourdan maxi.jourdan at wanadoo.fr
Wed Aug 1 12:33:16 PDT 2018


This is a Request for Comments for the amlogic (meson) video decoder driver.
It is written around the V4L2 M2M framework without using the Request
API as there are a hardware bitstream parser and firmwares.

It features decoding for:
- MPEG 1/2/4, H.263, H.264, MJPEG, HEVC 8-bit (partial)

Even though they are supported in hardware, it doesn't leverage support for:
- HEVC 10-bit, VP9, VC1 (all those are in TODOs)

The output is multiplanar NV12 (V4L2_PIX_FMT_NV12M).
Supported SoCs are: GXBB (S905), GXL (S905X/W/D), GXM (S912)
It was tested primarily with FFmpeg, GStreamer and kodi.

The file hierarchy can be boiled down to:

			| codec_h264.c
			| codec_mjpeg.c
			| codec_mpeg4.c
          | vdec_1.c -->| codec_mpeg12.c
vdec.c -->| vdec_hevc.c -->| codec_hevc.c
	  | esparser.c

The V4L2 code is handled mostly in vdec.c.
Each VDEC and CODEC unit is accessed via ops structs to facilitate the code.

The arrangement between vdecs and codecs can be seen in vdec_platform.c
This file also declares things like pixfmts, min/max buffers and firmware paths
for each SoC.

Specific questions about the code:

- While I do use the platform's general clks and resets tied to the vdec in
a nice way (dts + clock/reset controller with clk/reset frameworks),
there are some subclocks and resets that I use in the driver by writing
directly to registers. e.g:

	- writel_relaxed((1<<7) | (1<<6), core->dos_base + DOS_SW_RESET0);
	- writel_relaxed(0x3ff, core->dos_base + DOS_GCLK_EN0);

and a few other instances where that happens.

Is it okay to not create specific controllers for those ? The main issue is
the lack of documentation so I don't know which resets/clocks are impacted by
those writes.
The only thing I'm certain of is that they only apply to the vdec/esparser.

- I tend to call vdec_* functions from the codec handlers.

For instance, codec_h264 will call vdec_dst_buf_done_idx to DONE
a capture buffer. vdec_dst_buf_done_idx is as such a public symbol.

Should I use an ops struct for those instead, so that the codec handlers
don't depend directly on the vdec general code ?

- Naming: my public symbols either start with vdec_* or esparser_*

Should I change that to something meson/amlogic specific ?

- I have a _lot_ of writel_relaxed calls.

Can I leave them be or is there a nicer way to do it ?

- Since the decoder is single instance, I only allow one _open at a time.

However the v4l2 compliance suite complains about this.
How should I safely make it single instance ? Not allowing multiple start_streaming ?

- I am getting these 2 fails, but unsure what they are about:

Buffer ioctls:
	fail: ../../../v4l-utils-1.12.3/utils/v4l2-compliance/v4l2-test-buffers.cpp(428): node->node2 == NULL
	test VIDIOC_REQBUFS/CREATE_BUFS/QUERYBUF: FAIL
	fail: ../../../v4l-utils-1.12.3/utils/v4l2-compliance/v4l2-test-buffers.cpp(571): q.has_expbuf(node)
	test VIDIOC_EXPBUF: FAIL



And of course, I will gladly accept any kind of other feedback you would have.

Thanks!


Maxime Jourdan (4):
  media: meson: add v4l2 m2m video decoder driver
  ARM64: dts: meson-gx: add vdec entry
  ARM64: dts: meson: add vdec entries
  dt-bindings: media: add Amlogic Meson Video Decoder Bindings

 .../bindings/media/amlogic,meson-vdec.txt     |   60 +
 arch/arm64/boot/dts/amlogic/meson-gx.dtsi     |   14 +
 arch/arm64/boot/dts/amlogic/meson-gxbb.dtsi   |    8 +
 arch/arm64/boot/dts/amlogic/meson-gxl.dtsi    |    8 +
 arch/arm64/boot/dts/amlogic/meson-gxm.dtsi    |    4 +
 drivers/media/platform/Kconfig                |   10 +
 drivers/media/platform/meson/Makefile         |    1 +
 drivers/media/platform/meson/vdec/Makefile    |    7 +
 drivers/media/platform/meson/vdec/canvas.c    |   69 +
 drivers/media/platform/meson/vdec/canvas.h    |   42 +
 .../media/platform/meson/vdec/codec_h264.c    |  376 +++++
 .../media/platform/meson/vdec/codec_h264.h    |   13 +
 .../media/platform/meson/vdec/codec_helpers.c |   45 +
 .../media/platform/meson/vdec/codec_helpers.h |    8 +
 .../media/platform/meson/vdec/codec_hevc.c    | 1383 +++++++++++++++++
 .../media/platform/meson/vdec/codec_hevc.h    |   13 +
 .../media/platform/meson/vdec/codec_mjpeg.c   |  203 +++
 .../media/platform/meson/vdec/codec_mjpeg.h   |   13 +
 .../media/platform/meson/vdec/codec_mpeg12.c  |  183 +++
 .../media/platform/meson/vdec/codec_mpeg12.h  |   13 +
 .../media/platform/meson/vdec/codec_mpeg4.c   |  213 +++
 .../media/platform/meson/vdec/codec_mpeg4.h   |   13 +
 drivers/media/platform/meson/vdec/esparser.c  |  320 ++++
 drivers/media/platform/meson/vdec/esparser.h  |   16 +
 drivers/media/platform/meson/vdec/hevc_regs.h |  742 +++++++++
 drivers/media/platform/meson/vdec/vdec.c      | 1009 ++++++++++++
 drivers/media/platform/meson/vdec/vdec.h      |  152 ++
 drivers/media/platform/meson/vdec/vdec_1.c    |  266 ++++
 drivers/media/platform/meson/vdec/vdec_1.h    |   13 +
 drivers/media/platform/meson/vdec/vdec_hevc.c |  188 +++
 drivers/media/platform/meson/vdec/vdec_hevc.h |   22 +
 .../media/platform/meson/vdec/vdec_platform.c |  273 ++++
 .../media/platform/meson/vdec/vdec_platform.h |   29 +
 33 files changed, 5729 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/media/amlogic,meson-vdec.txt
 create mode 100644 drivers/media/platform/meson/vdec/Makefile
 create mode 100644 drivers/media/platform/meson/vdec/canvas.c
 create mode 100644 drivers/media/platform/meson/vdec/canvas.h
 create mode 100644 drivers/media/platform/meson/vdec/codec_h264.c
 create mode 100644 drivers/media/platform/meson/vdec/codec_h264.h
 create mode 100644 drivers/media/platform/meson/vdec/codec_helpers.c
 create mode 100644 drivers/media/platform/meson/vdec/codec_helpers.h
 create mode 100644 drivers/media/platform/meson/vdec/codec_hevc.c
 create mode 100644 drivers/media/platform/meson/vdec/codec_hevc.h
 create mode 100644 drivers/media/platform/meson/vdec/codec_mjpeg.c
 create mode 100644 drivers/media/platform/meson/vdec/codec_mjpeg.h
 create mode 100644 drivers/media/platform/meson/vdec/codec_mpeg12.c
 create mode 100644 drivers/media/platform/meson/vdec/codec_mpeg12.h
 create mode 100644 drivers/media/platform/meson/vdec/codec_mpeg4.c
 create mode 100644 drivers/media/platform/meson/vdec/codec_mpeg4.h
 create mode 100644 drivers/media/platform/meson/vdec/esparser.c
 create mode 100644 drivers/media/platform/meson/vdec/esparser.h
 create mode 100644 drivers/media/platform/meson/vdec/hevc_regs.h
 create mode 100644 drivers/media/platform/meson/vdec/vdec.c
 create mode 100644 drivers/media/platform/meson/vdec/vdec.h
 create mode 100644 drivers/media/platform/meson/vdec/vdec_1.c
 create mode 100644 drivers/media/platform/meson/vdec/vdec_1.h
 create mode 100644 drivers/media/platform/meson/vdec/vdec_hevc.c
 create mode 100644 drivers/media/platform/meson/vdec/vdec_hevc.h
 create mode 100644 drivers/media/platform/meson/vdec/vdec_platform.c
 create mode 100644 drivers/media/platform/meson/vdec/vdec_platform.h

-- 
2.17.1




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