AP_Compass: added retries during init for i2c devices

higher in init, lower for run

libraries/AP_Compass/AP_Compass_HMC5843.cpp

@@ -159,6 +159,9 @@ bool AP_Compass_HMC5843::init()
         return false;
     }
 
+    // high retries for init
+    _bus->set_retries(10);
+    
     if (!_bus->configure()) {
         hal.console->printf("HMC5843: Could not configure the bus\n");
         goto errout;
@@ -185,6 +188,9 @@ bool AP_Compass_HMC5843::init()
 
     _initialised = true;
 
+    // lower retries for run
+    _bus->set_retries(3);
+    
     bus_sem->give();
 
     // perform an initial read

libraries/AP_Compass/AP_Compass_HMC5843.h

@@ -89,6 +89,8 @@ public:
 
     // return 24 bit bus identifier
     virtual uint32_t get_bus_id(void) const = 0;
+
+    virtual void set_retries(uint8_t retries) {}
 };
 
 class AP_HMC5843_BusDriver_HALDevice : public AP_HMC5843_BusDriver
@@ -113,6 +115,10 @@ public:
     uint32_t get_bus_id(void) const override {
         return _dev->get_bus_id();
     }
+
+    void set_retries(uint8_t retries) override {
+        return _dev->set_retries(retries);
+    }
     
 private:
     AP_HAL::OwnPtr<AP_HAL::Device> _dev;

libraries/AP_Compass/AP_Compass_LIS3MDL.cpp

@@ -86,6 +86,9 @@ bool AP_Compass_LIS3MDL::init()
         dev->set_read_flag(0xC0);
     }
 
+    // high retries for init
+    dev->set_retries(10);
+    
     uint8_t whoami;
     if (!dev->read_registers(ADDR_WHO_AM_I, &whoami, 1) ||
         whoami != ID_WHO_AM_I) {
@@ -100,6 +103,9 @@ bool AP_Compass_LIS3MDL::init()
     dev->write_register(ADDR_CTRL_REG3, 0, true); // continuous
     dev->write_register(ADDR_CTRL_REG4, 0x0C, true); // z-axis ultra high perf
     dev->write_register(ADDR_CTRL_REG5, 0x40, true); // block-data-update
+
+    // lower retries for run
+    dev->set_retries(3);
     
     dev->get_semaphore()->give();