Here's the desired scenario:
- System is turned on
- Pi boots (bullseye) with HDMI off (fully off, not just outputting a blank stream)
- Later, Pi activates HDMI and starts outputting video
Currently, I cannot implement step 2 - all suggestions I have seen involve
vcgencmd or something similar executed in userland, which is much later. The reason for needing this functionality involves the custom displays I am to use and is non-negotiable.
First, does anyone know if this is possible on bullseye? If so, how?
Secondly, is there an idiot's guide to VC4 anyone suggests?
Open to (sensible) workarounds, and even compiling a kernel, just don't know where to start or what the most sensible route is.
Thanks in advance.
Edit I can't seem to find any documentation on VC6 (Pi4) - is it still using the same VC4 software? If so, the best I can find is https://www.kernel.org/doc/html/latest/gpu/vc4.html#hdmi-encoder but the line 'The driver’s HDMI encoder does not yet support power management. The HDMI encoder’s power domain and the HSM/pixel clocks are kept continuously running, and only the HDMI logic and packet ram are powered off/on at disable/enable time.' suggests that it is not possible at all.