AP_HAL_Linux: RCOutput_Bebop: group writes

This allows to remove the hard limit of 4 motors in Bebop, allowing to
execute the motor test.

libraries/AP_HAL_Linux/RCOutput_Bebop.cpp

@@ -319,15 +319,24 @@ void LinuxRCOutput_Bebop::write(uint8_t ch, uint16_t period_us)
 
     _request_period_us[ch] = period_us;
 
-    /* write command to motors only when all channels are set */
-    if (ch == (BEBOP_BLDC_MOTORS_NUM - 1)) {
+    if (!_corking)
+        push();
+}
+
+void LinuxRCOutput_Bebop::cork()
+{
+    _corking = true;
+}
+
+void LinuxRCOutput_Bebop::push()
+{
+    _corking = false;
     pthread_mutex_lock(&_mutex);
     memcpy(_period_us, _request_period_us, sizeof(_period_us));
     pthread_cond_signal(&_cond);
     pthread_mutex_unlock(&_mutex);
     memset(_request_period_us, 0 ,sizeof(_request_period_us));
 }
-}
 
 uint16_t LinuxRCOutput_Bebop::read(uint8_t ch)
 {

libraries/AP_HAL_Linux/RCOutput_Bebop.h

@@ -61,6 +61,8 @@ public:
     void     enable_ch(uint8_t ch);
     void     disable_ch(uint8_t ch);
     void     write(uint8_t ch, uint16_t period_us);
+    void     cork() override;
+    void     push() override;
     uint16_t read(uint8_t ch);
     void     read(uint16_t* period_us, uint8_t len);
     void     set_esc_scaling(uint16_t min_pwm, uint16_t max_pwm);
@@ -75,6 +77,7 @@ private:
     uint16_t _min_pwm;
     uint16_t _max_pwm;
     uint8_t  _state;
+    bool     _corking = false;
 
     uint8_t _checksum(uint8_t *data, unsigned int len);
     void _start_prop();