[PATCH v3 0/3] Enable Hantro G1 post-processor

[Ezequiel Garcia <ezequiel@collabora.com>]

Hi all,

The Hantro G1 VPU post-processor block can be pipelined with
the decoder hardware, allowing to perform operations such as
color conversion, scaling, rotation, cropping, among others.

When the post-processor is enabled, the decoder hardware
needs its own set of NV12 buffers (the native decoder format),
and the post-processor is the owner of the CAPTURE buffers,
allocated for the post-processed format.

This way, applications obtain post-processed
(scaled, converted, etc) buffers transparently.

This feature is implemented by exposing the post-processed pixel
formats on ENUM_FMT, ordered as "preferred pixelformat first":

v4l2-ctl -d 1 --list-formats
ioctl: VIDIOC_ENUM_FMT
	Type: Video Capture Multiplanar

	[0]: 'NV12' (Y/CbCr 4:2:0)
	[1]: 'YUYV' (YUYV 4:2:2)

The order of preference in ENUM_FMT can be used as a hint
by applications. This series updates the uAPI specification
accordingly.

When the application sets a pixel format other than NV12,
the post-processor is transparently enabled.

Patch 1 is a cleanups needed to easier integrate the post-processor.
Patch 2 introduces the post-processing support.
Patch 3 updates the uAPI specification.

This is tested on RK3288 platforms with MPEG-2, VP8 and
H264 streams, decoding to YUY2 surfaces. For now, this series
is only adding support for NV12-to-YUY2 conversion.

Applies to media/master.

Future plans
------------

It seems to me that we should start moving this driver to use
regmap-based access to registers. However, such move is out of scope
and not entirely related to this post-processor enablement.

We'll work on that as follow-up patches.

Changelog
---------

Changes v3:

* After discussing with Hans and Tomasz during the media summit
in ELCE, we decided to go back on the MC changes. The MC topology
is now untouched. This means the series is now similar to v1,
except we explicitly use the ENUM_FMT to hint about the post-processed
formats.

Changes v2:

* The decoder->post-processor topology is now exposed
  explicitly and applications need to configure the pipeline.
  By default, the decoder is enabled and the post-processor
  is disabled.

* RGB post-processing output has been dropped. We might
  add this in the future, but for now, it seems it would
  make the code more complex without a use-case in mind.
  RGB is much more memory-consuming so less attractive
  than YUV, and modern GPUs and display controllers support YUV.

* The post-processor implementation still supports RK3288
  only. However, a generic register infrastructure is introduced
  to make addition of other variants such as RK3399 really easy.

Ezequiel Garcia (3):
  media: hantro: Cleanup format negotiation helpers
  media: hantro: Support color conversion via post-processing
  media: vidioc-enum-fmt.rst: clarify format preference

 .../media/uapi/v4l/vidioc-enum-fmt.rst        |   4 +-
 drivers/staging/media/hantro/Makefile         |   1 +
 drivers/staging/media/hantro/hantro.h         |  64 +++++++-
 drivers/staging/media/hantro/hantro_drv.c     |   8 +-
 .../staging/media/hantro/hantro_g1_h264_dec.c |   2 +-
 .../media/hantro/hantro_g1_mpeg2_dec.c        |   2 +-
 drivers/staging/media/hantro/hantro_g1_regs.h |  53 +++++++
 .../staging/media/hantro/hantro_g1_vp8_dec.c  |   2 +-
 drivers/staging/media/hantro/hantro_h264.c    |   6 +-
 drivers/staging/media/hantro/hantro_hw.h      |  13 ++
 .../staging/media/hantro/hantro_postproc.c    | 141 ++++++++++++++++++
 drivers/staging/media/hantro/hantro_v4l2.c    | 105 ++++++++-----
 drivers/staging/media/hantro/rk3288_vpu_hw.c  |  10 ++
 13 files changed, 366 insertions(+), 45 deletions(-)
 create mode 100644 drivers/staging/media/hantro/hantro_postproc.c

-- 
2.22.0