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fix pwm_out: avoid race condition when setting mode

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Bootup failed in some cases with:
ERROR [mixer] can't reset mixers on /dev/pwm_output1

The reason was the mode change was not applied yet.
This commit is contained in:
Beat Küng 2021-04-12 17:05:53 +02:00 committed by Lorenz Meier
parent 18f17dcb96
commit faaee0f077
2 changed files with 22 additions and 4 deletions
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20
src/drivers/pwm_out/PWMOut.cpp
View File

@ -580,9 +580,9 @@ void PWMOut::Run()
// push backup schedule
ScheduleDelayed(_backup_schedule_interval_us);
if (_new_mode_request.load() != _mode) {
if (_new_mode_request.load() != MODE_NO_REQUEST) {
set_mode(_new_mode_request.load());
_new_mode_request.store(_mode);
_new_mode_request.store(MODE_NO_REQUEST);
}
_mixing_output.update();
@ -1762,6 +1762,22 @@ int PWMOut::fmu_new_mode(PortMode new_mode)
return OK;
}
void PWMOut::request_mode(Mode new_mode)
{
if (_new_mode_request.load() != MODE_NO_REQUEST) {
PX4_ERR("already being set"); // not expected to happen
return;
}
_new_mode_request.store(new_mode);
ScheduleNow();
// wait until processed
int max_time = 1000;
while (_new_mode_request.load() != MODE_NO_REQUEST && max_time-- > 0) {
px4_usleep(1000);
}
}
namespace
{

6
src/drivers/pwm_out/PWMOut.hpp
View File

@ -118,6 +118,8 @@ public:
MODE_4CAP,
MODE_5CAP,
MODE_6CAP,
MODE_NO_REQUEST
};
PWMOut() = delete;
@ -157,7 +159,7 @@ public:
int set_mode(Mode mode);
Mode get_mode() { return _mode; }
void request_mode(Mode new_mode) { _new_mode_request.store(new_mode); }
void request_mode(Mode new_mode);
static int set_i2c_bus_clock(unsigned bus, unsigned clock_hz);
@ -181,7 +183,7 @@ private:
Mode _mode{MODE_NONE};
px4::atomic<Mode> _new_mode_request{MODE_NONE};
px4::atomic<Mode> _new_mode_request{MODE_NO_REQUEST};
uint32_t _backup_schedule_interval_us{1_s};