From: Hans Verkuil <hans.verk...@cisco.com> This patch series is something I have been working on for some time now. The initial use-case was for the Allwinner A10 SoC which supported CEC but only by polling the CEC bus. It turned out that being able to access the CEC bus at such a low-level was also ideal for debugging CEC problems (bad timings etc) and to do error injection.
Since these old Allwinner SoCs aren't all that easy to get these days I decided to try to use the same code but using a GPIO pin on a Raspberry Pi (tested with both 2B and 3) since those are widely available. Of course, the cec-gpio driver can be used with any pull-up gpio on any SoC. This patch series first makes some small changes in the CEC framework (patches 1-4) to prepare for this CEC pin support. Patch 5-6 adds the new API elements and documents it. Patch 7 reworks the CEC core event handling. Patch 8 adds pin monitoring support (allows userspace to see all CEC pin transitions as they happen). Patch 9 adds the core cec-pin implementation that translates low-level pin transitions into valid CEC messages. Basically this does what any SoC with a proper CEC hardware implementation does. Patch 10-11 add a little cec-gpio driver that sits on top of the cec-pin code. Note that patch 10 is not quite complete: I want to add optional cec-notifier support as well so the gpio pin can be 'connected' to the HDMI controller and be notified when the physical address changes. Patch 12 adds an example dts snippet with support for cec-gpio to the Rpi dts. In the final version this should change to a Documentation/devicetree/bindings/media/cec-gpio.txt file. Patches 1-9 are basically ready for 4.14, although I will probably clean up a few things in cec-pin.c/h. Maxime, this series does not contain the A10 support yet. I have that in this (somewhat old) branch: https://git.linuxtv.org/hverkuil/media_tree.git/log/?h=cubie-cec-pin If you look in sun4i_hdmi_enc.c: https://git.linuxtv.org/hverkuil/media_tree.git/tree/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c?h=cubie-cec-pin and search for 'cec' you'll see that the CEC implementation is now tiny since all the work is now done in cec-pin.c. All that this driver needs to implement are the pin read/low/high ops which are literally one-liners. Once 4.13-rc1 is released I will rebase this patch series and add patches for the sun4i CEC driver. Eric, don't confuse this with the real Rpi CEC driver. As I mentioned to you in another email I'm waiting for 4.13-rc1 to be released and then I'll clean up my rpi patch series and repost for inclusion in 4.14. This gpio driver in combination with a Raspberry Pi is ideal for debugging since the rpi is so widely available. I will post a patch to the cec-ctl utility that supports this new pin monitoring API separately. It is able to fully analyze the CEC traffic, and esp. when using the GPIO interrupt it is also very accurate. And much, much cheaper than a full fledged CEC analyzer. And for the record, I've used this quite successfully at Cisco while debugging CEC issues :-) For those who are interested: some code for error injection is available here: https://git.linuxtv.org/hverkuil/media_tree.git/log/?h=cec-error-inj But it needs a lot more work, esp. with regards to the API design. So this is not planned for 4.14 but more likely 4.15. Regards, Hans Hans Verkuil (12): cec: improve transmit timeout logging cec: add *_ts variants for transmit_done/received_msg cec: add adap_free op cec-core.rst: document the adap_free callback linux/cec.h: add pin monitoring API support cec: document the new CEC pin capability, events and mode cec: rework the cec event handling cec: add core support for low-level CEC pin monitoring cec-pin: add low-level pin hardware support cec-gpio: add CEC GPIO driver MAINTAINERS: add cec-gpio entry rpi: add cec-gpio support to dts Documentation/media/kapi/cec-core.rst | 10 +- .../media/uapi/cec/cec-ioc-adap-g-caps.rst | 7 + Documentation/media/uapi/cec/cec-ioc-dqevent.rst | 20 + Documentation/media/uapi/cec/cec-ioc-g-mode.rst | 19 +- MAINTAINERS | 8 + arch/arm/boot/dts/bcm2836-rpi-2-b.dts | 5 + arch/arm64/boot/dts/broadcom/bcm2837-rpi-3-b.dts | 5 + drivers/media/Kconfig | 3 + drivers/media/cec/Makefile | 4 + drivers/media/cec/cec-adap.c | 196 ++++-- drivers/media/cec/cec-api.c | 73 +- drivers/media/cec/cec-core.c | 2 + drivers/media/cec/cec-pin.c | 784 +++++++++++++++++++++ drivers/media/platform/Kconfig | 10 + drivers/media/platform/Makefile | 2 + drivers/media/platform/cec-gpio/Makefile | 1 + drivers/media/platform/cec-gpio/cec-gpio.c | 214 ++++++ include/media/cec-pin.h | 113 +++ include/media/cec.h | 64 +- include/uapi/linux/cec.h | 8 +- 20 files changed, 1449 insertions(+), 99 deletions(-) create mode 100644 drivers/media/cec/cec-pin.c create mode 100644 drivers/media/platform/cec-gpio/Makefile create mode 100644 drivers/media/platform/cec-gpio/cec-gpio.c create mode 100644 include/media/cec-pin.h -- 2.11.0
