LinuxScheduler::init() was not really working as it should. This was the
result of "ps -Leo class,rtprio,wchan,comm | grep ArduCopter":
FF 12 futex_ ArduCopter.elf
FF 12 usleep ArduCopter.elf
FF 12 hrtime ArduCopter.elf
FF 12 poll_s ArduCopter.elf
FF 12 hrtime ArduCopter.elf
FF 12 hrtime ArduCopter.elf
As can be seen all the threads run with the same priority, the one of the main
thread. There were basically 2 mistakes:
1) pthread_attr_setschedpolicy() needs to be called before
pthread_attr_setschedparam(). Otherwise the latter will just return
an error and not set the priority
2) pthread_create() defaults to ignore the priority and inherit the
it from the parent thread. pthread_attr_setinheritsched() needs to
be called to change the behavior to PTHREAD_EXPLICIT_SCHED. See
pthread_attr_setinheritsched(3) for an example program to test the
behaviors.
Also, it's undefined behavior to call pthread_attr_init() several times on the
same pthread_attr_t. Although we could reutilize the same attribute without
calling pthread_attr_init() again, lets refactor the code a little bit, so all
the pthread calls are in a single place. Then also call pthread_attr_destroy()
when we are done.
In Linux the default stack size is always greater than 32k, either 2MB
or 8MB depending on the architecture. There's no point in creating a
function to lock 32k.
Falls back to baro if range finder is unavailable
Adds parameter enabling user to select which height source (baro or range finder) will be used during optical flow nav.
In AP_MotorsTri.cpp the AP_MOTORS_MOT_1, _2 and _4 constants are
always mapped to actual output channels through _motor_to_channel_map
while the _CH_TRI_YAW is not, but there were a few inconsistencies
in this that could lead to things like PWM min and max values being
set on wrong channels.
It looks like all in all _motor_to_channel_map being in PROGMEM
probably doesn't help save memory and I'm not sure how useful it is
in the first place but regardless the usage should be consistent.
When performing a u-turn in AUTO (waypoints are 180deg turn from each other) sometimes the aircraft can't decide to turn left or right and wobbled back and forth a couple times. There was existing code to solve this but it was not executing all the time like when in LOITER mode. Frankly, I don't understand the criteria that was required to make it execute and i suspect there is still a gremlin in that logic but just executing the check all the time makes prevents the wobble behavior.
this allows a HAL_PARAM_DEFAULTS_PATH to be specified for a build to
override the default parameters for a build. This is useful to build a
firmware that has different default parameters
