Fixed RX task check.

[mikeller]

Fixes #10647.

We need to run the entire task check every time, to avoid losing status updates while waiting for the main task to be scheduled.

[SteveCEvans]

I’ve just ordered an R-XSR to investigate this. The check function takes a lot of time so it would be better to preserve the state as required between calls. I’ll raise another PR with a fix that gives optimal timing once I’ve been able to reproduce this.

[mikeller]

Yeah, there is potentially quite a bit of optimisation possible, by moving some of the state updating that is currently done in the check function into the actual task.
Also, splitting the check function into multiple functions, one for each RX type, and calling them by function pointer which is set up during initialisation.
But for now this will be a workaround that is no worse than the old way of doing things.

[TheIsotopes]

@mikeller I have tested this and it works, but unfortunately the cpu load goes to 100% when the transmitter is switched on.

[SteveCEvans]

The check function is quite time consuming, so we really only want to be calling it once. What state is being lost to cause the FrSky rx not to work?

[mikeller]

@TheIsotopes: Thanks for testing - the feedback was helpful. Turns out this was a bug in the state machine - if there are no updates pending we need to go back to checking, and not busy wait in the processing state. Please try again:

betaflight_4.3.0_STM32F745_82ff9fb00.zip
betaflight_4.3.0_STM32F7X2_82ff9fb00.zip
betaflight_4.3.0_STM32F411_82ff9fb00.zip
betaflight_4.3.0_STM32F405_82ff9fb00.zip

[TheIsotopes]

@mikeller cpu load is normal and telemetry is working ... but there are still problems with the rx task.
see also my last comment in #10647.

# tasks
Task list             rate/hz  max/us  avg/us maxload avgload  total/ms
00 - (         SYSTEM)     10       5       1    0.5%    0.5%         0
01 - (         SYSTEM)    996       6       1    1.0%    0.5%        87
02 - (           GYRO)   8000      13       8   10.9%    6.9%      7137
03 - (         FILTER)   8000      24      16   19.7%   13.3%     14817
04 - (            PID)   8000      61      44   49.3%   35.7%     39354
07 - (             RX)  29412      17      12   50.5%   35.7%       444
08 - (         SERIAL)    100     810       2    8.6%    0.5%        54
09 - (       DISPATCH)    998       6       1    1.0%    0.5%        60
10 - (BATTERY_VOLTAGE)     50       7       2    0.5%    0.5%        11
11 - (BATTERY_CURRENT)     50       4       1    0.5%    0.5%         4
12 - ( BATTERY_ALERTS)      5       6       2    0.5%    0.5%         1
13 - (         BEEPER)    100      10       2    0.6%    0.5%        14
21 - (       LEDSTRIP)    100      28       6    0.7%    0.5%        59
25 - (            CMS)     20       7       2    0.5%    0.5%         3
26 - (        VTXCTRL)      5       5       1    0.5%    0.5%         0
27 - (        CAMCTRL)      5       2       0    0.5%    0.0%         0
29 - (    ADCINTERNAL)      1       5       3    0.5%    0.5%         0
RX Check Function                  12       2                        85
Total (excluding SERIAL)                       137.7%   97.1%

EDIT: Stick command also not working e.g. calibrate Gyro

EDIT2: fixed in #10659