Hi all,
During the Linux Plumbers Conference we (i.e. V4L2 and DRM developers) had a discussion on how to handle the CEC protocol that's part of the HDMI standard.
The decision was made to create a CEC bus with CEC clients, each represented by a /dev/cecX device. So this is independent of the V4L or DRM APIs.
In addition interested subsystems (alsa for the Audio Return Channel, and possibly networking as well for ethernet over HDMI) can intercept/send CEC messages as well if needed. Particularly for the CEC additions made in HDMI 1.4a it is no longer possible to handle the CEC protocol completely in userspace, but part of the intelligence has to be moved to kernelspace.
I've started working on this API but I am still at the stage of playing around with it and thinking about the best way this functionality should be exposed. At least I managed to get the first CEC packets transferred today :-)
It will probably be a few weeks before I post something, but in the meantime if you want to use CEC and have certain requirements that need to be met, please let me know. If only so that I can be certain I haven't forgotten anything.
Regards,
Hans