diff --git a/os/hal/include/hal_sio.h b/os/hal/include/hal_sio.h
index 533afa865..c45d98f12 100644
--- a/os/hal/include/hal_sio.h
+++ b/os/hal/include/hal_sio.h
@@ -618,7 +618,9 @@ extern "C" {
   void sioObjectInit(SIODriver *siop);
   msg_t sioStart(SIODriver *siop, const SIOConfig *config);
   void sioStop(SIODriver *siop);
+  void sioStartOperationI(SIODriver *siop, const SIOOperation *operation);
   void sioStartOperation(SIODriver *siop, const SIOOperation *operation);
+  void sioStopOperationI(SIODriver *siop);
   void sioStopOperation(SIODriver *siop);
   void sioWriteEnableFlags(SIODriver *siop, sioflags_t flags);
   void sioSetEnableFlags(SIODriver *siop, sioflags_t flags);
diff --git a/os/hal/lib/complex/buffered_sio/hal_buffered_sio.c b/os/hal/lib/complex/buffered_sio/hal_buffered_sio.c
index ab9a601fb..43c25baff 100644
--- a/os/hal/lib/complex/buffered_sio/hal_buffered_sio.c
+++ b/os/hal/lib/complex/buffered_sio/hal_buffered_sio.c
@@ -156,7 +156,6 @@ msg_t bsdStart(BufferedSIODriver *bsdp, const BufferedSIOConfig *config) {
 
   osalDbgCheck(bsdp != NULL);
 
-  osalSysLock();
   osalDbgAssert((bsdp->state == BS_STOP) || (bsdp->state == BS_READY),
                 "invalid state");
 
@@ -167,15 +166,16 @@ msg_t bsdStart(BufferedSIODriver *bsdp, const BufferedSIOConfig *config) {
 
   msg = sioStart(bsdp->siop, config);
   if (msg == HAL_RET_SUCCESS) {
-    sioStartOperation(bsdp->siop, &bs_default_operation);
+    osalSysLock();
+    sioStartOperationI(bsdp->siop, &bs_default_operation);
+    sioWriteEnableFlagsI(bsdp->siop, SIO_FL_ALL);
     bsdp->state = BS_READY;
+    osalSysUnlock();
   }
   else {
     bsdp->state = BS_STOP;
   }
 
-  osalSysUnlock();
-
   return msg;
 }
 
@@ -192,8 +192,6 @@ void bsdStop(BufferedSIODriver *bsdp) {
 
   osalDbgCheck(bsdp != NULL);
 
-  osalSysLock();
-
   osalDbgAssert((bsdp->state == BS_STOP) || (bsdp->state == BS_READY),
                 "invalid state");
 
@@ -205,10 +203,10 @@ void bsdStop(BufferedSIODriver *bsdp) {
 
   bsdp->state = BS_STOP;
 
-  oqResetI(&bsdp->oqueue);
+  osalSysLock();
+  oqResetI(&bsdp->oqueue); /* TODO should go in the upper class.*/
   iqResetI(&bsdp->iqueue);
   osalOsRescheduleS();
-
   osalSysUnlock();
 }
 
diff --git a/os/hal/src/hal_sio.c b/os/hal/src/hal_sio.c
index 20593b8e5..d6bccb68d 100644
--- a/os/hal/src/hal_sio.c
+++ b/os/hal/src/hal_sio.c
@@ -304,13 +304,12 @@ void sioStop(SIODriver *siop) {
  *                          be @p NULL if callbacks are not required
  *                          encoding the operation to be performed
  *
- * @api
+ * @iclass
  */
-void sioStartOperation(SIODriver *siop, const SIOOperation *operation) {
+void sioStartOperationI(SIODriver *siop, const SIOOperation *operation) {
 
   osalDbgCheck(siop != NULL);
-
-  osalSysLock();
+  osalDbgCheckClassI();
 
   osalDbgAssert((siop->state == SIO_READY) ||
                 (siop->state == SIO_ACTIVE), "invalid state");
@@ -326,7 +325,7 @@ void sioStartOperation(SIODriver *siop, const SIOOperation *operation) {
 
   if (siop->state == SIO_READY) {
     sio_lld_start_operation(siop);
-    siop->state     = SIO_ACTIVE;
+    siop->state = SIO_ACTIVE;
 
 #if SIO_USE_SYNCHRONIZATION == TRUE
     /* If synchronization is enabled then some events are enforced by
@@ -335,7 +334,22 @@ void sioStartOperation(SIODriver *siop, const SIOOperation *operation) {
                          SIO_FL_ALL_DATA | SIO_FL_ALL_ERRORS | SIO_FL_ALL_PROTOCOL);
 #endif
   }
+}
 
+/**
+ * @brief   Starts a SIO operation.
+ *
+ * @param[in] siop          pointer to an @p SIODriver structure
+ * @param[in] operation     pointer to an @p SIOOperation structure, can
+ *                          be @p NULL if callbacks are not required
+ *                          encoding the operation to be performed
+ *
+ * @api
+ */
+void sioStartOperation(SIODriver *siop, const SIOOperation *operation) {
+
+  osalSysLock();
+  sioStartOperationI(siop, operation);
   osalSysUnlock();
 }
 
@@ -344,13 +358,12 @@ void sioStartOperation(SIODriver *siop, const SIOOperation *operation) {
  *
  * @param[in] siop      pointer to an @p SIODriver structure
  *
- * @api
+ * @iclass
  */
-void sioStopOperation(SIODriver *siop) {
+void sioStopOperationI(SIODriver *siop) {
 
   osalDbgCheck(siop != NULL);
-
-  osalSysLock();
+  osalDbgCheckClassI();
 
   osalDbgAssert((siop->state == SIO_READY) ||
                 (siop->state == SIO_ACTIVE), "invalid state");
@@ -369,7 +382,21 @@ void sioStopOperation(SIODriver *siop) {
     siop->operation = NULL;
     siop->state     = SIO_READY;
   }
+}
 
+/**
+ * @brief   Stops an ongoing SIO operation, if any.
+ *
+ * @param[in] siop      pointer to an @p SIODriver structure
+ *
+ * @api
+ */
+void sioStopOperation(SIODriver *siop) {
+
+  osalDbgCheck(siop != NULL);
+
+  osalSysLock();
+  sioStopOperationI(siop);
   osalSysUnlock();
 }