[PATCH/RFC 0/5] HDMI driver for Samsung S5PV310 platform

[Tomasz Stanislawski <t.stanislaws@samsung.com>]

==============
 Introduction
==============

The purpose of this RFC is to discuss the driver for a TV output interface
available in upcoming Samsung SoC. The HW is able to generate digital and
analog signals. Current version of the driver supports only digital output.

Internally the driver uses videobuf2 framework, and CMA memory allocator.  Not
all of them are merged by now, but I decided to post the sources to start
discussion driver's design.

======================
 Hardware description
======================

The SoC contains a few HW sub-blocks:

1. Video Processor (VP). It is used for processing of NV12 data.  An image
stored in RAM is accessed by DMA. Pixels are cropped, scaled. Additionally,
post processing operations like brightness, sharpness and contrast adjustments
could be performed. The output in YCbCr444 format is send to Mixer.

2. Mixer (MXR). The piece of hardware responsible for mixing and blending
multiple data inputs before passing it to an output device.  The MXR is capable
of handling up to three image layers. One is the output of VP.  Other two are
images in RGB format (multiple variants are supported).  The layers are scaled,
cropped and blended with background color.  The blending factor, and layers'
priority are controlled by MXR's registers. The output is passed either to HDMI
or TVOUT.

3. HDMI. The piece of HW responsible for generation of HDMI packets. It takes
pixel data from mixer and transforms it into data frames. The output is send
to HDMIPHY interface.

4. HDMIPHY. Physical interface for HDMI. Its duties are sending HDMI packets to
HDMI connector. Basically, it contains a PLL that produces source clock for
Mixer, VP and HDMI during streaming.

5. TVOUT. Generation of TV analog signal. (driver not implemented)

6. VideoDAC. Modulator for TVOUT signal. (driver not implemented)


The diagram below depicts connection between all HW pieces.
                    +-----------+
NV12 data ---dma--->|   Video   |
                    | Processor |
                    +-----------+
                          |
                          V
                    +-----------+
RGB data  ---dma--->|           |
                    |   Mixer   |
RGB data  ---dma--->|           |
                    +-----------+
                          |
                          * dmux
                         /
                  +-----*   *------+
                  |                |
                  V                V
            +-----------+    +-----------+
            |    HDMI   |    |   TVOUT   |
            +-----------+    +-----------+
                  |                |
                  V                V
            +-----------+    +-----------+
            |  HDMIPHY  |    |  VideoDAC |
            +-----------+    +-----------+
                  |                |
                  V                V
                HDMI           Composite
             connector         connector


==================
 Driver interface
==================

The posted driver implements three V4L2 nodes. Every video node implements V4L2
output buffer. One of nodes corresponds to input of Video Processor. The other
two nodes correspond to RGB inputs of Mixer. All nodes share the same output.
It is one of the Mixer's outputs: TVOUT or HDMI. Changing output in one layer
using S_OUTPUT would change outputs of all other video nodes. The same thing
happens if one try to reconfigure output i.e. by calling S_DV_PRESET. However
it not possible to change or reconfigure the output while streaming. To sum up,
all features in posted version of driver goes as follows:

1. QUERYCAP
2. S_FMT, G_FMT - single and multiplanar API
  a) node named video0 supports formats NV12, NV12, NV12T (tiled version of
NV12), NV12MT (multiplane version of NV12T).
  b) nodes named graph0 and graph1 support formats RGB565, ARGB1555, ARGB4444,
ARGB8888.
3. Buffer with USERPTR and MMAP memory.
4. Streaming and buffer control. (STREAMON, STREAMOFF, REQBUF, QBUF, DQBUF)
5. OUTPUT enumeration.
6. DV preset control (SET, GET, ENUM). Currently modes 480P59_94, 720P59_94,
1080P30, 1080P59_94 and 1080P60 work.
7. Positioning layer's window on output display using S_CROP, G_GROP, CROPCAP.
8. Positioning and cropping data in buffer using S_CROP, G_GROP, CROPCAP with
buffer type OVERLAY. *

TODOs:
- add analog TVOUT driver
- add S_OUTPUT
- add S_STD ioctl
- add control of alpha blending / chroma keying via V4L2 controls
- add controls for luminance curve and sharpness in VP
- consider exporting all output functionalities to separate video node
- consider media controller framework
- better control over debugging
- fix dependency between all TV drivers

* The need of cropping in source buffers came from problem with MFC driver for
S5P. The MFC supports only width divisible by 64. If a width of a decoded movie
is not aligned do 64 then padding pixels are filled with zeros. This is an ugly
green color in YCbCr colorspace. Filling it with zeros by a CPU is a waste of
resources since an image can be cropped in VP. Is it possible to set crops for
user data for M2M devices. V4L2 lacks such functionality of non-M2M devices.
Therefore cropping in buffer V4L2_BUF_TYPE_VIDEO_OVERLAY was used as an work
around.

=====================
 Device Architecture
=====================

Three drivers are added in this patch.

1. HDMIPHY. It is an I2C driver for HDMIPHY interface. It exports following
callback by V4L2 subdevice:
- s_power: currently stub
- s_stream: configures and starts/stops HDMIPHY
- s_dv_preset: used to choose proper frequency of clock for other TV devices

2. HDMI. The auxiliary driver used to control HDMI interface. It exports its
subdev to a subdev pool for use by other drivers. The following callbacks are
implemented:
- s_power: runs HDMI hardware, regulators and clocks.
- s_stream: runs HDMIPHY and starts generation of video frames.
- enum_dv_presets
- s_dv_preset
- g_mbus_format: returns information on data format expected by on HDMI input
  The driver supports an interrupt. It is used to detect plug/unplug events in
kernel debugs.  The API for detection of such an events in V4L2 API is to be
defined.

3. Mixer & Video Processor driver. It is called 's5p-mixer' because of
historical reasons. It was decided combine VP and MXR drivers into one because
of shared interrupt and very similar interface via V4L2 nodes. The driver is a
realization of many-to-many relation between multiple input layers and multiple
outputs. All shared resources are kept in struct mxr_device. It provides
utilities for management and synchronization of access to resources and
reference counting. The outputs are obtained from subdev pool basing on names
supplied in platform data. One layer is a single video node. Since layers
differs simple inheritance is applied. Every layer type implements set of ops.
There are different ops for Mixer layers and other for VP layer.

The videobuf2 framework was used for the management of buffers and streaming.
All other V4L2 ioctls are processed in layers common interface. The CMA was
used as memory allocator for Mixer's buffers. It could be easily exchanged with
any other allocator integrated with videobuf2 framework.

Driver is not yet integrated with power domain driver. Moreover one of mixer's
clocks has to change parent while entering streaming mode. Therefore all power
and clock management was moved to platform data until final solutions emerges.

===============
 Usage summary
===============

Follow steps below to display double-buffered animation on HDMI output.

01. Open video node named graph0.
02. S_FMT(type = OUTPUT, pixelformat = V4L2_PIX_FMT_RGB*, width, height, ...)
03. REQ_BUFS(type = OUTPUT, memory = MMAP, count = 2)
04. MMAP(type = OUTPUT, index = 0)
05. MMAP(type = OUTPUT, index = 1)
06. Fill buffer 0 with data
07. QBUF(type = OUTPUT, index = 0)
08. STREAM_ON(type = OUTPUT)
09. Fill buffer 1 with data
10. QBUF(type = OUTPUT, index = 1)
11. DQBUF(type = OUTPUT)
12. QBUF(type = OUTPUT, index = 0)
13. DQBUF(type = OUTPUT)
14. Goto 09

===============
 Patch Summary
===============

Tomasz Stanislawski (5):
  i2c-s3c2410: fix I2C dedicated for hdmiphy
  universal: i2c: add I2C controller 8 (HDMIPHY)
  v4l: add macro for 1080p59_54 preset
  s5p-tv: add driver for HDMI output on S5PC210 platform
  s5pc210: add s5p-tv to platform devices

 arch/arm/mach-s5pv310/Kconfig                   |    7 +
 arch/arm/mach-s5pv310/Makefile                  |    1 +
 arch/arm/mach-s5pv310/clock.c                   |  132 ++-
 arch/arm/mach-s5pv310/dev-tv.c                  |  450 ++++++
 arch/arm/mach-s5pv310/include/mach/irqs.h       |    8 +
 arch/arm/mach-s5pv310/include/mach/map.h        |   27 +
 arch/arm/mach-s5pv310/include/mach/regs-clock.h |   15 +
 arch/arm/plat-samsung/Kconfig                   |    5 +
 arch/arm/plat-samsung/Makefile                  |    1 +
 arch/arm/plat-samsung/dev-i2c8.c                |   68 +
 arch/arm/plat-samsung/include/plat/devs.h       |    3 +
 arch/arm/plat-samsung/include/plat/iic.h        |    1 +
 arch/arm/plat-samsung/include/plat/tv.h         |   36 +
 drivers/i2c/busses/i2c-s3c2410.c                |   36 +-
 drivers/media/video/Kconfig                     |    8 +
 drivers/media/video/Makefile                    |    1 +
 drivers/media/video/s5p-tv/Kconfig              |   42 +
 drivers/media/video/s5p-tv/Makefile             |   15 +
 drivers/media/video/s5p-tv/hdmi.h               |   74 +
 drivers/media/video/s5p-tv/hdmi_drv.c           |  795 ++++++++++
 drivers/media/video/s5p-tv/hdmiphy.h            |   37 +
 drivers/media/video/s5p-tv/hdmiphy_drv.c        |  228 +++
 drivers/media/video/s5p-tv/mixer.h              |  281 ++++
 drivers/media/video/s5p-tv/mixer_drv.c          |  362 +++++
 drivers/media/video/s5p-tv/mixer_grp_layer.c    |  181 +++
 drivers/media/video/s5p-tv/mixer_reg.c          |  532 +++++++
 drivers/media/video/s5p-tv/mixer_reg.h          |   44 +
 drivers/media/video/s5p-tv/mixer_video.c        |  834 ++++++++++
 drivers/media/video/s5p-tv/mixer_vp_layer.c     |  202 +++
 drivers/media/video/s5p-tv/regs-hdmi.h          | 1849 +++++++++++++++++++++++
 drivers/media/video/s5p-tv/regs-vmx.h           |  196 +++
 drivers/media/video/s5p-tv/regs-vp.h            |  277 ++++
 drivers/media/video/v4l2-common.c               |    1 +
 include/linux/videodev2.h                       |    1 +
 34 files changed, 6748 insertions(+), 2 deletions(-)
 create mode 100644 arch/arm/mach-s5pv310/dev-tv.c
 create mode 100644 arch/arm/plat-samsung/dev-i2c8.c
 create mode 100644 arch/arm/plat-samsung/include/plat/tv.h
 create mode 100644 drivers/media/video/s5p-tv/Kconfig
 create mode 100644 drivers/media/video/s5p-tv/Makefile
 create mode 100644 drivers/media/video/s5p-tv/hdmi.h
 create mode 100644 drivers/media/video/s5p-tv/hdmi_drv.c
 create mode 100644 drivers/media/video/s5p-tv/hdmiphy.h
 create mode 100644 drivers/media/video/s5p-tv/hdmiphy_drv.c
 create mode 100644 drivers/media/video/s5p-tv/mixer.h
 create mode 100644 drivers/media/video/s5p-tv/mixer_drv.c
 create mode 100644 drivers/media/video/s5p-tv/mixer_grp_layer.c
 create mode 100644 drivers/media/video/s5p-tv/mixer_reg.c
 create mode 100644 drivers/media/video/s5p-tv/mixer_reg.h
 create mode 100644 drivers/media/video/s5p-tv/mixer_video.c
 create mode 100644 drivers/media/video/s5p-tv/mixer_vp_layer.c
 create mode 100644 drivers/media/video/s5p-tv/regs-hdmi.h
 create mode 100644 drivers/media/video/s5p-tv/regs-vmx.h
 create mode 100644 drivers/media/video/s5p-tv/regs-vp.h

-- 
1.7.3.5