[PATCHv11 00/17] HDMI CEC framework

Hans Verkuil hverkuil at xs4all.nl
Fri Feb 5 15:27:43 UTC 2016

From: Hans Verkuil <hans.verkuil at cisco.com>

Hi all,

The eleventh version of this patchset addresses the comments 2 and 3 I made
when I posted the previous version. I am now much happier about those parts
of the API. It also implements a bunch of bug fixes and adds CEC emulation
to the vivid driver.

The one remaining open item is to decide what to do if a cable is disconnected
and reconnected for a source: should the CEC adapter be disabled and re-enabled?
Which means that you need to reconfigure. Or just update the physical address
from the EDID (if necessary)? I think the latter, but I need to analyze this
more closely.

I might decide to leave this for now since this issue does not affect the

The cec-ctl and cec-compliance utilities used to test the CEC framework
can be found here:


Best regards,


Changes since v10
- Split the msg.status field into tx_status and rx_status.
- Add counters for various CEC protocol errors that can occur during
- Add tx_status bits for the ARB_LOST and NACK status and add a generic
- Add retry support to the CEC framework for hardware that does not have
  retry support.
- Improve event handling: on open() generate events that report the initial
  CEC adapter status and the number of connected inputs. Also ensure that
  you never loose important events (intermediate events may be lost, but
  never the last event). The basic mechanism has been taken from the V4L2
  event implementation which works very well.
- CEC emulation support was added to vivid which makes it much easier to
  test CEC applications without having hardware present.
- Improve handling of timings and timeouts in the cec framework.
- Improve locking.
- Fixed buggy rc cleanup.
- All CEC messages are now fully supported in cec-funcs.h (specifically
  handling of UI Commands and short audio descriptors).

Changes since v9
- Updated cec.txt
- Added a promiscuous capability to signal those adapters that can monitor
  all CEC traffic, not just directed and broadcast messages. I have one
  adapter that can do this. Added code in the framework to handle such
  messages correctly.
- The status field is now value and no longer a bitmask.
- Renamed the kernel config from CEC to MEDIA_CEC
- The adap_transmit() callback now has a retries argument.
- Use the new CEC_MAX_MSG_SIZE define instead of hardcoding it as 16
- Add support to wait for a reply after a broadcast message: this was
  forbidden, but it is a valid use-case.
- Make sure you can't send a message to yourself.
- Waiting for a transmit to succeed would never timeout (and couldn't be
  interrupted). Fixed.
- The message status was not updated correctly if it was CEC_MSG_FEATURE_ABORTed.
- Fixed a nasty kernel oops when deleting a cec adapter.
- Removed the owner check: the module owner is NULL if it is compiled into
  the kernel instead of as a module.
- Added separate register/unregister calls: this is safer and actually made
  it possible to drop the ugly 'cec_ready' v4l2_subdev op. Suggested by
  Russell, and that was a good idea.
- Added missing support for 32-bit to 64-bit ioctl conversion.
- Move the v4l2_subdev cec ops into a v4l2_subdev_cec_ops struct.

Changes since v8
- Addressed the comments Russell King made about how the cec character
  devices should be allocated/freed.
- Updated the DocBook documentation.

Changes since v7

- I thought that the core thread could handle out-of-order messages, but that
  turned out to be wrong. After careful analysis I realized that I had to
  rewrite this part in cec.c in order to make it work.
- Added new CEC-specific keys to input.h and use them in the CEC rc keymap.
  these are media operations and not the Pause key on the keyboard.
- Added CEC_PHYS_ADDR_INVALID (0xffff)
- Added monitor support to monitor CEC traffic
- Replaced CAP_TRANSMIT and CAP_RECEIVE by a single CAP_IO.
- Replaced CAP_CDC by CAP_CDC_HPD since this only applies to the HPD part of
  the CDC messages.
- Add ninputs field to cec_caps to export the number of inputs of the device.
- Drop CEC_LOG_ADDRS_FL_HANDLE_MSGS and the flags field (see next change for
  more info).
- Add CEC_CLAIM and CEC_RELEASE to explicitly start/stop processing CEC messages.
  This also implies ownership of the CEC interface, so other filehandles can
  only receive but not transmit.
- Reworked event handling: report adapter state changes, input changes and
  if the message receive queue is full.
- cec-funcs.h: added CDC HEC support.
- Renamed G/S_ADAP ioctls to ADAP_G/S: this made it clearer which ioctls deal
  with the adapter configuration and which deal with CEC messages/events.
- Clarified which CEC messages are passed on to userspace and which aren't.
  Specifically if CAP_ARC is set, then all ARC messages are handled by the kernel.
  If CAP_CDC_HPD is set, then all CDC hotplug messages are handled by the kernel.
  Otherwise these messages are passed on to userspace.

Changes since v6
- added cec-funcs.h to provide wrapper functions that fill in the cec_msg struct.
  This header is needed both by the kernel and by applications.
- fix a missing rc_unregister_device call.
- added CEC support for the adv7842 and cobalt drivers.
- added CEC operand defines. Rename CEC message defines to CEC_MSG_ and operand
  defines now use CEC_OP_.
- the CEC_VERSION defines are dropped since we now have the CEC_OP_VERSION defines.
- cec-ioc-g-adap-log-addrs.xml: document cec_versions field.
- cec-ioc-g-caps.xml: drop vendor_id and version fields.
- add MAINTAINERS entry.
- add CDC support (not yet fully functional).
- add a second debug level for message debugging.
- fix a nasty kernel Oops in cec_transmit_msg while waiting for transmit completion
  (adap->tx_queue[idx].func wasn't set to NULL).
- add support for CEC_MSG_REPORT_FEATURES (CEC 2.0 only).
- correctly abort unsupported messages.
- add support for the device power status feature.
- add support for the audio return channel (preliminary).
- add support for the CDC hotplug message (preliminary).
- added osd_name to struct cec_log_addrs.
- reported physical addresses are stored internally.
- fix enabling/disabling the CEC adapter (internal fields weren't cleared correctly).
- zero reserved fields.
- return an error if you try to receive/transmit and the adapter isn't configured.
- when creating the adapter provide the owner module and the parent device.
- add a CEC_VENDOR_ID_NONE define to signal if no vendor ID was set.
- add new capabilities: RC (remote control), ARC (audio return channel) and CDC
  (Capability Discovery and Control).
- applications that want to handle messages for a logical address need to set the
  CEC_LOG_ADDRS_FL_HANDLE_MSGS flag. Otherwise the CEC core will be the one handling
  all messages.
- Each logical address has its own all_device_types value. So this should be an array,
  not a single value.
- I'm sure I've forgotten some changes...

Changes since v5
- drop struct cec_timeval in favour of a __u64 that keeps the timestamp in ns
- remove userspace documentation from Documentation/cec.txt as userspace API
  is described in the DocBook
- add missing documentation for the passthrough mode to the DocBook
- add information about the number of events that can be queued
- fix misspelling of reply
- fix behaviour of posting an event in cec_received_msg, such that the behaviour
  is consistent with the documentation

Changes since v4
- add sequence numbering to transmitted messages
- add sequence number handling to event hanlding
- add passthrough mode
- change reserved field sizes
- fixed CEC version defines and addec CEC 2.0 commands
- add DocBook documentation

Changes since v3
- remove the promiscuous mode
- rewrite the devicetree patches
- fixes, expansion and partial rewrite of the documentation
- reorder of API structures and addition of reserved fields
- use own struct to report time (32/64 bit safe)
- fix of handling events
- add cec.h to include/uapi/linux/Kbuild
- fixes in the adv76xx driver (add missing methods, change adv7604 to adv76xx)
- cleanup of debug messages in s5p-cec driver
- remove non necessary claiming of a gpio in the s5p-cec driver
- cleanup headers of the s5p-cec driver

Changes since v2
- added promiscuous mode
- added new key codes to the input framework
- add vendor ID reporting
- add the possibility to clear assigned logical addresses
- cleanup of the rc cec map

Changes since v1
- documentation edited and moved to the Documentation folder
- added key up/down message handling
- add missing CEC commands to the cec.h file


The work on a common CEC framework was started over three years ago by Hans
Verkuil. Unfortunately the work has stalled. As I have received the task of
creating a driver for the CEC interface module present on the Exynos range of
SoCs, I got in touch with Hans. He replied that the work stalled due to his
lack of time.

Original RFC by Hans Verkuil/Martin Bugge

Hans Verkuil (11):
  input.h: add BUS_CEC type
  cec: add HDMI CEC framework
  cec: add compat32 ioctl support
  cec.txt: add CEC framework documentation
  DocBook/media: add CEC documentation
  v4l2-subdev: add HDMI CEC ops
  cec: adv7604: add cec support.
  cec: adv7842: add cec support
  cec: adv7511: add cec support.
  cobalt: add cec support
  vivid: add CEC emulation

Kamil Debski (6):
  dts: exynos4*: add HDMI CEC pin definition to pinctrl
  dts: exynos4: add node for the HDMI CEC device
  dts: exynos4412-odroid*: enable the HDMI CEC device
  HID: add HDMI CEC specific keycodes
  rc: Add HDMI CEC protocol handling
  cec: s5p-cec: Add s5p-cec driver

 Documentation/DocBook/device-drivers.tmpl          |    3 +
 Documentation/DocBook/media/Makefile               |    2 +
 Documentation/DocBook/media/v4l/biblio.xml         |   10 +
 Documentation/DocBook/media/v4l/cec-api.xml        |   76 +
 Documentation/DocBook/media/v4l/cec-func-close.xml |   59 +
 Documentation/DocBook/media/v4l/cec-func-ioctl.xml |   73 +
 Documentation/DocBook/media/v4l/cec-func-open.xml  |   94 +
 Documentation/DocBook/media/v4l/cec-func-poll.xml  |   89 +
 .../DocBook/media/v4l/cec-ioc-adap-g-caps.xml      |  167 ++
 .../DocBook/media/v4l/cec-ioc-adap-g-log-addrs.xml |  305 +++
 .../DocBook/media/v4l/cec-ioc-adap-g-phys-addr.xml |   80 +
 .../DocBook/media/v4l/cec-ioc-adap-g-state.xml     |   87 +
 .../DocBook/media/v4l/cec-ioc-adap-g-vendor-id.xml |   70 +
 Documentation/DocBook/media/v4l/cec-ioc-claim.xml  |   71 +
 .../DocBook/media/v4l/cec-ioc-dqevent.xml          |  252 +++
 .../DocBook/media/v4l/cec-ioc-g-monitor.xml        |   86 +
 .../DocBook/media/v4l/cec-ioc-g-passthrough.xml    |   81 +
 .../DocBook/media/v4l/cec-ioc-receive.xml          |  247 +++
 Documentation/DocBook/media_api.tmpl               |    6 +-
 Documentation/cec.txt                              |  348 ++++
 .../devicetree/bindings/media/s5p-cec.txt          |   31 +
 Documentation/video4linux/vivid.txt                |   36 +-
 MAINTAINERS                                        |   21 +
 arch/arm/boot/dts/exynos4.dtsi                     |   12 +
 arch/arm/boot/dts/exynos4210-pinctrl.dtsi          |    7 +
 arch/arm/boot/dts/exynos4210-universal_c210.dts    |    4 +
 arch/arm/boot/dts/exynos4x12-pinctrl.dtsi          |    7 +
 drivers/media/Kconfig                              |    7 +
 drivers/media/Makefile                             |    2 +
 drivers/media/cec.c                                | 2160 ++++++++++++++++++++
 drivers/media/i2c/adv7511.c                        |  366 +++-
 drivers/media/i2c/adv7604.c                        |  243 ++-
 drivers/media/i2c/adv7842.c                        |  257 ++-
 drivers/media/pci/cobalt/Kconfig                   |    1 +
 drivers/media/pci/cobalt/cobalt-driver.c           |  111 +-
 drivers/media/pci/cobalt/cobalt-driver.h           |    2 +
 drivers/media/pci/cobalt/cobalt-irq.c              |    3 +
 drivers/media/pci/cobalt/cobalt-v4l2.c             |  126 +-
 drivers/media/pci/cobalt/cobalt-v4l2.h             |    2 +
 drivers/media/platform/Kconfig                     |   12 +
 drivers/media/platform/Makefile                    |    1 +
 drivers/media/platform/s5p-cec/Makefile            |    2 +
 drivers/media/platform/s5p-cec/exynos_hdmi_cec.h   |   37 +
 .../media/platform/s5p-cec/exynos_hdmi_cecctrl.c   |  208 ++
 drivers/media/platform/s5p-cec/regs-cec.h          |   96 +
 drivers/media/platform/s5p-cec/s5p_cec.c           |  289 +++
 drivers/media/platform/s5p-cec/s5p_cec.h           |   76 +
 drivers/media/platform/vivid/Kconfig               |    1 +
 drivers/media/platform/vivid/vivid-core.c          |  309 ++-
 drivers/media/platform/vivid/vivid-core.h          |   23 +
 drivers/media/platform/vivid/vivid-vid-cap.c       |   23 +
 drivers/media/platform/vivid/vivid-vid-common.c    |   61 +
 drivers/media/platform/vivid/vivid-vid-common.h    |    1 +
 drivers/media/rc/keymaps/Makefile                  |    1 +
 drivers/media/rc/keymaps/rc-cec.c                  |  174 ++
 drivers/media/rc/rc-main.c                         |    1 +
 fs/compat_ioctl.c                                  |   19 +
 include/media/cec.h                                |  200 ++
 include/media/i2c/adv7511.h                        |    6 +-
 include/media/rc-core.h                            |    1 +
 include/media/rc-map.h                             |    5 +-
 include/media/v4l2-subdev.h                        |   21 +
 include/uapi/linux/Kbuild                          |    2 +
 include/uapi/linux/cec-funcs.h                     | 1852 +++++++++++++++++
 include/uapi/linux/cec.h                           |  912 +++++++++
 include/uapi/linux/input-event-codes.h             |   28 +
 include/uapi/linux/input.h                         |    1 +
 67 files changed, 9898 insertions(+), 68 deletions(-)
 create mode 100644 Documentation/DocBook/media/v4l/cec-api.xml
 create mode 100644 Documentation/DocBook/media/v4l/cec-func-close.xml
 create mode 100644 Documentation/DocBook/media/v4l/cec-func-ioctl.xml
 create mode 100644 Documentation/DocBook/media/v4l/cec-func-open.xml
 create mode 100644 Documentation/DocBook/media/v4l/cec-func-poll.xml
 create mode 100644 Documentation/DocBook/media/v4l/cec-ioc-adap-g-caps.xml
 create mode 100644 Documentation/DocBook/media/v4l/cec-ioc-adap-g-log-addrs.xml
 create mode 100644 Documentation/DocBook/media/v4l/cec-ioc-adap-g-phys-addr.xml
 create mode 100644 Documentation/DocBook/media/v4l/cec-ioc-adap-g-state.xml
 create mode 100644 Documentation/DocBook/media/v4l/cec-ioc-adap-g-vendor-id.xml
 create mode 100644 Documentation/DocBook/media/v4l/cec-ioc-claim.xml
 create mode 100644 Documentation/DocBook/media/v4l/cec-ioc-dqevent.xml
 create mode 100644 Documentation/DocBook/media/v4l/cec-ioc-g-monitor.xml
 create mode 100644 Documentation/DocBook/media/v4l/cec-ioc-g-passthrough.xml
 create mode 100644 Documentation/DocBook/media/v4l/cec-ioc-receive.xml
 create mode 100644 Documentation/cec.txt
 create mode 100644 Documentation/devicetree/bindings/media/s5p-cec.txt
 create mode 100644 drivers/media/cec.c
 create mode 100644 drivers/media/platform/s5p-cec/Makefile
 create mode 100644 drivers/media/platform/s5p-cec/exynos_hdmi_cec.h
 create mode 100644 drivers/media/platform/s5p-cec/exynos_hdmi_cecctrl.c
 create mode 100644 drivers/media/platform/s5p-cec/regs-cec.h
 create mode 100644 drivers/media/platform/s5p-cec/s5p_cec.c
 create mode 100644 drivers/media/platform/s5p-cec/s5p_cec.h
 create mode 100644 drivers/media/rc/keymaps/rc-cec.c
 create mode 100644 include/media/cec.h
 create mode 100644 include/uapi/linux/cec-funcs.h
 create mode 100644 include/uapi/linux/cec.h


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