diff --git a/os/hal/hal.dox b/os/hal/hal.dox
index 0af849111..308477567 100644
--- a/os/hal/hal.dox
+++ b/os/hal/hal.dox
@@ -440,44 +440,54 @@
   digraph example {
     size="5, 7";
     rankdir="LR";
-    node [shape=circle, fontname=Helvetica, fontsize=8, fixedsize="true", width="0.8", height="0.8"];
+    node [shape=circle, fontname=Helvetica, fontsize=8, fixedsize="true", width="0.9", height="0.9"];
     edge [fontname=Helvetica, fontsize=8];
-    uninit [label="CAN_UNINIT", style="bold"];
+
     stop  [label="CAN_STOP\nLow Power"];
+    uninit [label="CAN_UNINIT", style="bold"];
+    starting [label="CAN_STARTING\nInitializing"];
     ready [label="CAN_READY\nClock Enabled"];
     sleep [label="CAN_SLEEP\nLow Power"];
-    uninit -> stop [label="canInit()"];
-    stop -> stop [label="canStop()"];
-    stop -> ready [label="canStart()"];
-    ready -> stop [label="canStop()"];
-    ready -> ready [label="canReceive()\ncanTransmit()"];
-    ready -> ready [label="canStart()"];
-    ready -> sleep [label="canSleep()"];
-    sleep -> sleep [label="canSleep()"];
-    sleep -> ready [label="canWakeup()"];
-    sleep -> ready [label="wakeup event"];
+
+    uninit -> stop [label=" canInit()", constraint=false];
+    stop -> stop [label="\ncanStop()"];
+    stop -> ready [label="\ncanStart()\n(fast implementation)"];
+    stop -> starting [label="\ncanStart()\n(slow implementation)"];
+    starting -> starting [label="\ncanStart()\n(other thread)"];
+    starting -> ready [label="\ninitialization complete\n(all threads)"];
+    ready -> stop [label="\ncanStop()"];
+    ready -> ready [label="\ncanStart()\ncanReceive()\ncanTransmit()"];
+    ready -> sleep [label="\ncanSleep()"];
+    sleep -> sleep [label="\ncanSleep()"];
+    sleep -> ready [label="\ncanWakeup()"];
+    sleep -> ready [label="\nhardware\nwakeup event"];
   }
  * @enddot
  * @else
  * @dot
   digraph example {
     rankdir="LR";
-    node [shape=circle, fontname=Helvetica, fontsize=8, fixedsize="true", width="0.8", height="0.8"];
+    node [shape=circle, fontname=Helvetica, fontsize=8, fixedsize="true", width="0.9", height="0.9"];
     edge [fontname=Helvetica, fontsize=8];
-    uninit [label="CAN_UNINIT", style="bold"];
+
     stop  [label="CAN_STOP\nLow Power"];
+    uninit [label="CAN_UNINIT", style="bold"];
+    starting [label="CAN_STARTING\nInitializing"];
     ready [label="CAN_READY\nClock Enabled"];
     sleep [label="CAN_SLEEP\nLow Power"];
-    uninit -> stop [label="canInit()"];
-    stop -> stop [label="canStop()"];
-    stop -> ready [label="canStart()"];
-    ready -> stop [label="canStop()"];
-    ready -> ready [label="canReceive()\ncanTransmit()"];
-    ready -> ready [label="canStart()"];
-    ready -> sleep [label="canSleep()"];
-    sleep -> sleep [label="canSleep()"];
-    sleep -> ready [label="canWakeup()"];
-    sleep -> ready [label="wakeup event"];
+
+    uninit -> stop [label=" canInit()", constraint=false];
+    stop -> stop [label="\ncanStop()"];
+    stop -> ready [label="\ncanStart()\n(fast implementation)"];
+    stop -> starting [label="\ncanStart()\n(slow implementation)"];
+    starting -> starting [label="\ncanStart()\n(other thread)"];
+    starting -> ready [label="\ninitialization complete\n(all threads)"];
+    ready -> stop [label="\ncanStop()"];
+    ready -> ready [label="\ncanStart()\ncanReceive()\ncanTransmit()"];
+    ready -> sleep [label="\ncanSleep()"];
+    sleep -> sleep [label="\ncanSleep()"];
+    sleep -> ready [label="\ncanWakeup()"];
+    sleep -> ready [label="\nhardware\nwakeup event"];
   }
  * @enddot
  * @endif
@@ -510,7 +520,7 @@
  * @dot
   digraph example {
     rankdir="LR";
-    node [shape=circle, fontname=Helvetica, fontsize=8, fixedsize="true", width="0.8", height="0.8"];
+    node [shape=circle, fontname=Helvetica, fontsize=8, fixedsize="true", width="0.9", height="0.9"];
     edge [fontname=Helvetica, fontsize=8];
     uninit [label="PWM_UNINIT", style="bold"];
     stop  [label="PWM_STOP\nLow Power"];
@@ -592,7 +602,7 @@
   digraph example {
     size="5, 7";
     rankdir="LR";
-    node [shape=circle, fontname=Helvetica, fontsize=8, fixedsize="true", width="0.8", height="0.8"];
+    node [shape=circle, fontname=Helvetica, fontsize=8, fixedsize="true", width="0.9", height="0.9"];
     edge [fontname=Helvetica, fontsize=8];
 
     any [label="Any State"];
@@ -632,7 +642,7 @@
  * @dot
   digraph example {
     rankdir="LR";
-    node [shape=circle, fontname=Helvetica, fontsize=8, fixedsize="true", width="0.8", height="0.8"];
+    node [shape=circle, fontname=Helvetica, fontsize=8, fixedsize="true", width="0.9", height="0.9"];
     edge [fontname=Helvetica, fontsize=8];
 
     any [label="Any State"];
@@ -711,7 +721,7 @@
  * @dot
   digraph example {
     rankdir="LR";
-    node [shape=circle, fontname=Helvetica, fontsize=8, fixedsize="true", width="0.8", height="0.8"];
+    node [shape=circle, fontname=Helvetica, fontsize=8, fixedsize="true", width="0.9", height="0.9"];
     edge [fontname=Helvetica, fontsize=8];
 
     uninit [label="UART_UNINIT", style="bold"];
@@ -734,7 +744,7 @@
  * @dot
   digraph example {
     rankdir="LR";
-    node [shape=circle, fontname=Helvetica, fontsize=8, fixedsize="true", width="0.8", height="0.8"];
+    node [shape=circle, fontname=Helvetica, fontsize=8, fixedsize="true", width="0.9", height="0.9"];
     edge [fontname=Helvetica, fontsize=8];
 
     tx_idle [label="TX_IDLE", style="bold"];
@@ -760,7 +770,7 @@
  * @dot
   digraph example {
     rankdir="LR";
-    node [shape=circle, fontname=Helvetica, fontsize=8, fixedsize="true", width="0.8", height="0.8"];
+    node [shape=circle, fontname=Helvetica, fontsize=8, fixedsize="true", width="0.9", height="0.9"];
     edge [fontname=Helvetica, fontsize=8];
 
     rx_idle [label="RX_IDLE", style="bold"];
diff --git a/os/hal/platforms/STM32/can_lld.c b/os/hal/platforms/STM32/can_lld.c
index 526ecb98e..d8e12af9e 100644
--- a/os/hal/platforms/STM32/can_lld.c
+++ b/os/hal/platforms/STM32/can_lld.c
@@ -236,11 +236,10 @@ void can_lld_start(CANDriver *canp) {
         cfp->FR1 = 0;
         cfp->FR2 = 0;
       }
-      cfp++;
-      fmask <<= 1;
       /* Gives a chance for preemption since this is a rather long loop.*/
       chSysUnlock();
-      chThdYield();
+      cfp++;
+      fmask <<= 1;
       chSysLock();
     }
   }
diff --git a/os/hal/src/can.c b/os/hal/src/can.c
index a1fb237f3..ec907de97 100644
--- a/os/hal/src/can.c
+++ b/os/hal/src/can.c
@@ -81,6 +81,9 @@ void canObjectInit(CANDriver *canp) {
 
 /**
  * @brief   Configures and activates the CAN peripheral.
+ * @note    Activating the CAN bus can be a slow operation this this function
+ *          is not atomic, it waits internally for the initialization to
+ *          complete.
  *
  * @param[in] canp      pointer to the @p CANDriver object
  * @param[in] config    pointer to the @p CANConfig object
@@ -95,8 +98,7 @@ void canStart(CANDriver *canp, const CANConfig *config) {
   chDbgAssert((canp->cd_state == CAN_STOP) ||
               (canp->cd_state == CAN_STARTING) ||
               (canp->cd_state == CAN_READY),
-              "canStart(), #1",
-              "invalid state");
+              "canStart(), #1", "invalid state");
   while (canp->cd_state == CAN_STARTING)
     chThdSleepS(1);
   if (canp->cd_state == CAN_STOP) {
@@ -120,8 +122,7 @@ void canStop(CANDriver *canp) {
 
   chSysLock();
   chDbgAssert((canp->cd_state == CAN_STOP) || (canp->cd_state == CAN_READY),
-              "canStop(), #1",
-              "invalid state");
+              "canStop(), #1", "invalid state");
   can_lld_stop(canp);
   chSemResetI(&canp->cd_rxsem, 0);
   chSemResetI(&canp->cd_txsem, 0);
@@ -146,8 +147,8 @@ void canStop(CANDriver *canp) {
  *                      .
  * @return              The operation result.
  * @retval RDY_OK       the frame has been queued for transmission.
- * @retval RDY_TIMEOUT  operation not finished within the specified time.
- * @retval RDY_RESET    driver stopped while waiting.
+ * @retval RDY_TIMEOUT  The operation has timed out.
+ * @retval RDY_RESET    The driver has been stopped while waiting.
  *
  * @api
  */
@@ -157,8 +158,7 @@ msg_t canTransmit(CANDriver *canp, const CANTxFrame *ctfp, systime_t timeout) {
 
   chSysLock();
   chDbgAssert((canp->cd_state == CAN_READY) || (canp->cd_state == CAN_SLEEP),
-              "canTransmit(), #1",
-              "invalid state");
+              "canTransmit(), #1", "invalid state");
   while ((canp->cd_state == CAN_SLEEP) || !can_lld_can_transmit(canp)) {
     msg_t msg = chSemWaitTimeoutS(&canp->cd_txsem, timeout);
     if (msg != RDY_OK) {
@@ -187,10 +187,8 @@ msg_t canTransmit(CANDriver *canp, const CANTxFrame *ctfp, systime_t timeout) {
  *                      .
  * @return              The operation result.
  * @retval RDY_OK       a frame has been received and placed in the buffer.
- * @retval RDY_TIMEOUT  operation not finished within the specified time or
- *                      frame not immediately available if invoked using
- *                      @p TIME_IMMEDIATE.
- * @retval RDY_RESET    driver stopped while waiting.
+ * @retval RDY_TIMEOUT  The operation has timed out.
+ * @retval RDY_RESET    The driver has been stopped while waiting.
  *
  * @api
  */
@@ -200,8 +198,7 @@ msg_t canReceive(CANDriver *canp, CANRxFrame *crfp, systime_t timeout) {
 
   chSysLock();
   chDbgAssert((canp->cd_state == CAN_READY) || (canp->cd_state == CAN_SLEEP),
-              "canReceive(), #1",
-              "invalid state");
+              "canReceive(), #1", "invalid state");
   while ((canp->cd_state == CAN_SLEEP) || !can_lld_can_receive(canp)) {
     msg_t msg = chSemWaitTimeoutS(&canp->cd_rxsem, timeout);
     if (msg != RDY_OK) {
@@ -251,8 +248,7 @@ void canSleep(CANDriver *canp) {
 
   chSysLock();
   chDbgAssert((canp->cd_state == CAN_READY) || (canp->cd_state == CAN_SLEEP),
-              "canSleep(), #1",
-              "invalid state");
+              "canSleep(), #1", "invalid state");
   if (canp->cd_state == CAN_READY) {
     can_lld_sleep(canp);
     canp->cd_state = CAN_SLEEP;
@@ -275,8 +271,7 @@ void canWakeup(CANDriver *canp) {
 
   chSysLock();
   chDbgAssert((canp->cd_state == CAN_READY) || (canp->cd_state == CAN_SLEEP),
-              "canWakeup(), #1",
-              "invalid state");
+              "canWakeup(), #1", "invalid state");
   if (canp->cd_state == CAN_SLEEP) {
     can_lld_wakeup(canp);
     canp->cd_state = CAN_READY;