Consider new hotspot channel selection

[trickeydan]

We currently hardcode the WiFi channel for the hotspot. We should make this an option in Astoria.toml so that we can change it without changing code.

[RealOrangeOne]

Are we not able to let the Pi chose the best channel at the time? At a competition event, whatever the default channel is is probably going to get pretty crowded.

[trickeydan]

Are we not able to let the Pi chose the best channel at the time? At a competition event, whatever the default channel is is probably going to get pretty crowded.

That sounds like a separate thing to me and also is a much larger and complex task to implement scanning and channel selection. There's a thing in the kernel for ACS, but we'd need to test it with the Pi WiFi driver and things.

[RealOrangeOne]

Ah I see, I had thought it was as simple as pick_the_best_channel = true. I agree if it's something we'd have to implement ourselves it's a separate thing probably not worth doing for a while.

[trickeydan]

Ah I see, I had thought it was as simple as pick_the_best_channel = true

It is sometimes. We need to make sure that both the kernel and hostapd are being compiled with ACS enabled (I haven't checked yet), that the Broadcom driver supports it (this is the biggest question) and then we need to add the config option to hostapd.

Unfortunately hostapd silently fails if any of the above isn't true, so I'd rather we were really sure. The fallback mechanism appears to be a random channel.

[raccube]

The other approach would be to manually do a network scan before starting the hotspot to find an uncongested channel. However that would delay the start of the hotspot.