Wifi: switch tasks at interrupt level 1

[bugadani]

Closes #3160

Previously, we used both Software1 and the timer interrupt to switch tasks. Software1 runs at priority level 3, while the timer ran at level 2. Trying to run the timer at level 1 meant esp-wifi crashed because the Interrupt Option and the High Priority interrupt option work a bit differently.

The root cause of the issue is that level 1 interrupt handling restores PS directly from the stack, while higher interrupt levels restore it into EPSn, and then that gets moved into PS by the rfi instruction.

This PR fixes this problem by using Software0, which is a level 1 priority interrupt.

[MabezDev]

I think I'd prefer this fix, but based on the description of #3165, this fix doesn't work for esp32?

[bugadani]

Yes, the ESP32 doesn't have a free software interrupt at priority level 1, and other CPU interrupts like Timer can't be triggered from software.

[bugadani]

I guess we can pick this PR for chips except ESP32, and the other one for ESP32?

[MabezDev]

I think that makes sense. It's a bit annoying to have a esp32 workaround, but I don't see the point in making all the chips suffer the perf hit of the other work around. What do you think @bjoernQ?

[bjoernQ]

I think that makes sense. It's a bit annoying to have a esp32 workaround, but I don't see the point in making all the chips suffer the perf hit of the other work around. What do you think @bjoernQ?

Good idea (and yes having different code for ESP32 is very annoying but it's not the first time ESP32 needs something special)! Would be a shame to let the S3 suffer from this

[MabezDev]

LGTM, thanks!

[bjoernQ]

Thanks