remove panda fan fallback

[elkoled]

To remove the panda fan fallback (fan_set_power(30) on heartbeat loss), these are the states where the fan would be at 0%:

• Build
• AGNOS update
• pandad dead

Build and AGNOS update run before pandad starts. For this case we could add Panda().set_fan_power(30) in launch_chffrplus.sh before agnos_init.

Pandad dead can be a risk if other processes draw significant power with no fan control.

All three states draw significant power (>1 W), so the relative power saving from deactivating the fan (~50 mW) is low.

[elkoled]

@adeebshihadeh

[adeebshihadeh]

I still think this is good to do. What do you think @robbederks?

[robbederks]

If the SOM is up we might as well spin the fan if there's no heartbeat. Relying on the panda python class to work on agnos init sounds like a bad idea.

What's the goal of removing it? Power savings?

[adeebshihadeh]

If the SOM is up we might as well spin the fan if there's no heartbeat.

How do you know it's up? We recently had a bug with this.

What's the goal of removing it?

Simplification. Fan runs when actively commanded, otherwise it does not run.

[robbederks]

If it's annoying to maintain I'm ok with removing it. Are we keeping the GPIO controlled fan turn on from the xbl?

[adeebshihadeh]

No, any reason to keep this?