- With RPi4 the new setting enable_tvout has been introduced since composite video output is disabled by default on RPi4 as of performance reasons. Does this settings have any effect on prior RPi models, thus can composite output be disabled there via enable_tvout=0?
- There is an undocumented settings available that allowed to disable composite video on prior RPi models as well: hdmi_ignore_composite. AFAIK in combination with hdmi_ignore_hotplug this allows to disable the whole video pipeline and has thus the same effect as tvservice -o, just from early boot, not recoverable without reboot: https://github.com/raspberrypi/userland/issues/447
So the question is now if this old setting is obsolete, or if the one has an effect on RPi4 only while the other one affects prior RPi models only. Or do both handle things differently, so it could make sense to set both to have most video features disabled, thus most power saved on headless systems?
- On earlier RPi models there were gpu_mem_256/512/1024 to set GPU memory share for models with this amount of memory only. AFAIK the gpu_mem value borders for all RPi4 models (1G/2G/4G) is the same as for prior 1G models, thus is gpu_mem_1024 as well effective on all RPi4 models, or only the 1G one, or are there _2048/4096 settings available now, or must gpu_mem=XXX be used? Too many question in one sentence, sorry .
- Last but not least, I recognised that vcgencmd get_config sdram_freq always reports 0 on RPi4. The default according to docs is 3200. Reading through some overclocking threads here, no one ever sets this on RPi4. Is the sdram freq simply hardcoded on RPi4?