Plane: start logging when first needed

ArduPlane/ArduPlane.pde

@@ -164,6 +164,9 @@ DataFlash_Empty DataFlash;
 #endif
 #endif
 
+// has a log download started?
+static bool in_log_download;
+
 // scaled roll limit based on pitch
 static int32_t roll_limit_cd;
 static int32_t pitch_limit_min_cd;

ArduPlane/GCS_Mavlink.pde

@@ -2182,7 +2182,17 @@ mission_failed:
         break;
     }
 
-    case MAVLINK_MSG_ID_LOG_REQUEST_LIST ... MAVLINK_MSG_ID_LOG_REQUEST_END:
+    case MAVLINK_MSG_ID_LOG_REQUEST_DATA:
+    case MAVLINK_MSG_ID_LOG_ERASE:
+        in_log_download = true;
+        // fallthru
+    case MAVLINK_MSG_ID_LOG_REQUEST_LIST:
+        if (!in_mavlink_delay) {
+            handle_log_message(msg, DataFlash);
+        }
+        break;
+    case MAVLINK_MSG_ID_LOG_REQUEST_END:
+        in_log_download = false;
         if (!in_mavlink_delay) {
             handle_log_message(msg, DataFlash);
         }

ArduPlane/system.pde

@@ -142,9 +142,6 @@ static void init_ardupilot()
             gcs[i].reset_cli_timeout();
         }
     }
-    if (g.log_bitmask != 0) {
-        start_logging();
-    }
 #endif
 
     // Register mavlink_delay_cb, which will run anytime you have
@@ -624,5 +621,9 @@ static bool should_log(uint32_t mask)
     } else {
         armed = arming.is_armed();
     }
-    return armed || (g.log_bitmask & MASK_LOG_WHEN_DISARMED) != 0;
+    bool ret = armed || (g.log_bitmask & MASK_LOG_WHEN_DISARMED) != 0;
+    if (ret && !DataFlash.logging_started() && !in_log_download) {
+        start_logging();
+    }
+    return ret;
 }