fix(dronecan): address sensei-hacker review feedback on PR #11560

- Replace empty switch cases in handle_NodeStatus with (void)nodeStatus + TODO
- Remove volatile from main-loop-only canTxDropped/canTxQueueHWM
- Use __HAL_CAN_DISABLE_IT() instead of HAL_CAN_DeactivateNotification()
  in canTxDrainQueue (ISR context safety)

Author: daijoubu

src/main/drivers/dronecan/dronecan.c

@@ -389,34 +389,8 @@ static void handle_NodeStatus(CanardInstance *ins, CanardRxTransfer *transfer) {
     }
 
 
-    switch (nodeStatus.health) {
-    case UAVCAN_PROTOCOL_NODESTATUS_HEALTH_OK:
-        break;
-    case UAVCAN_PROTOCOL_NODESTATUS_HEALTH_WARNING:
-        break;
-    case UAVCAN_PROTOCOL_NODESTATUS_HEALTH_ERROR:
-        break;
-    case UAVCAN_PROTOCOL_NODESTATUS_HEALTH_CRITICAL:
-        break;
-    default:
-        break;
-    }
-
-
-    switch(nodeStatus.mode) {
-    case UAVCAN_PROTOCOL_NODESTATUS_MODE_OPERATIONAL:
-        break;
-    case UAVCAN_PROTOCOL_NODESTATUS_MODE_INITIALIZATION:
-        break;
-    case UAVCAN_PROTOCOL_NODESTATUS_MODE_MAINTENANCE:
-        break;
-    case UAVCAN_PROTOCOL_NODESTATUS_MODE_SOFTWARE_UPDATE:
-        break;
-    case UAVCAN_PROTOCOL_NODESTATUS_MODE_OFFLINE:
-        break;
-    default:
-        break;
-    }
+    // TODO: NodeStatus health/mode monitoring — currently no action taken
+    (void)nodeStatus;
 }
 
 static void handle_GNSSAuxiliary(CanardInstance *ins, CanardRxTransfer *transfer) {

src/main/drivers/dronecan/libcanard/canard_stm32f7xx_driver.c

@@ -54,8 +54,9 @@ static CAN_HandleTypeDef hcan1;
 // canTxDropped and canTxQueueHWM are written by main loop (canTxQueuePush), read by main loop only.
 // canRxBufferHWM is written by ISR (rxBufferPushFrame), read by main loop only.
 // All are uint8/uint16 so reads are single-instruction atomic on Cortex-M.
-static volatile uint16_t canTxDropped = 0;
-static volatile uint8_t  canTxQueueHWM = 0;
+// Only canRxBufferHWM needs volatile (ISR vs main loop sharing).
+static uint16_t canTxDropped = 0;
+static uint8_t  canTxQueueHWM = 0;
 static volatile uint8_t  canRxBufferHWM = 0;
 
 /* --- Initialization --- */
@@ -509,7 +510,10 @@ static void canTxDrainQueue(CAN_HandleTypeDef *hcan) {
         canTxQueueConsume();
     }
     if (canTxQueueIsEmpty()) {
-        HAL_CAN_DeactivateNotification(hcan, CAN_IT_TX_MAILBOX_EMPTY);
+        // Use the register-level macro instead of HAL_CAN_DeactivateNotification:
+        // this function is called from ISR context (TX mailbox complete callbacks)
+        // where HAL functions using __HAL_LOCK() may not be safe to call.
+        __HAL_CAN_DISABLE_IT(hcan, CAN_IT_TX_MAILBOX_EMPTY);
     }
 }