drivers/usbdev: CDC/ACM should reset all 'irregular' notifications to zero...

drivers/usbdev:  CDC/ACM should reset all 'irregular' notifications to zero after sending the SerialState packet.

drivers/usbdev/cdcacm.c

@@ -703,6 +703,10 @@ static int cdcacm_serialstate(FAR struct cdcacm_dev_s *priv)
     }
 
 errout_with_flags:
+  /* Reset all of the "irregular" notification */
+
+  priv->serialstate &= CDC_UART_CONSISTENT;
+
   leave_critical_section(flags);
   return ret;
 }
@@ -2117,7 +2121,7 @@ static int cdcuart_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
 #ifdef CONFIG_CDCACM_IFLOWCONTROL
         /* Report state of input flow control */
 
-        termiosp->c_lflag = (priv->iflow) ? CRTS_IFLOW : 0;
+        termiosp->c_cflag |= (priv->iflow) ? CRTS_IFLOW : 0;
 #endif
       }
       break;

include/nuttx/usb/cdc.h

@@ -419,6 +419,8 @@
                                           * 105 and RS-232 signal RTS.
                                           */
 
+/* CDC/ACM friendly naming */
+
 #define CDCACM_UART_DTR         CDC_DTE_PRESENT
 #define CDCACM_UART_RTS         CDC_ACTIVATE_CARRIER
 
@@ -547,9 +549,21 @@
                                           * overrun in the device.
                                           */
 
+/* CDC/ACM friendly naming */
+
 #define CDCACM_UART_DCD          CDC_UART_RXCARRIER
 #define CDCACM_UART_DSR          CDC_UART_TXCARRIER
 
+/* "SerialState is used like a real interrupt status register. Once a notification has been
+ *  sent, the device will reset and reevaluate the different signals.  For the consistent
+ *  signals like carrier detect or transmission carrier, this will mean another notification
+ *  will not be generated until there is a state change.  For the irregular signals like
+ *  break, the incoming ring signal, or the overrun error state, this will reset their values
+ *  to zero and again will not send another notification until their state changes."
+ */
+
+#define CDC_UART_CONSISTENT     (CDC_UART_RXCARRIER | CDC_UART_TXCARRIER)
+
 /* Table 70: Call State Change Value Definitions */
 
 #define CDC_CALLST_IDLE         0x01 /* Call has become idle */