SAME70 driver xTXDescriptorSemaphore issue (#1033)

* Fixes and issue with the SAME70 port where and error in gmac_dev_write() causes the counting  xTXDescriptorSemaphore to not be returned and eventually exhausting it.

* fix formatting

* Allows release of the network buffer if gmac_dev_write() fails and the ero-copy driver is being used.
Thanks @htibosch

* Fix typo

---------

Co-authored-by: Emil Popov <[email protected]>
Co-authored-by: tony-josi-aws <[email protected]>
Co-authored-by: ActoryOu <[email protected]>

Author: 4 people

source/portable/NetworkInterface/DriverSAM/NetworkInterface.c

@@ -651,12 +651,22 @@ static BaseType_t prvSAM_NetworkInterfaceOutput( NetworkInterface_t * pxInterfac
         if( ulResult != GMAC_OK )
         {
             TX_STAT_INCREMENT( tx_write_fail );
+
+            /* On a successful write to GMAC, the ownership of the TX descriptor will eventually get returned back to the network
+             * driver and prvEMACHandlerTask will give back the xTXDescriptorSemaphore counting semaphore. In this case however,
+             * writing to the GMAC failed, so there will be no EMAC_IF_TX_EVENT sent to prvEMACHandlerTask and the counting
+             * semaphore will not be given back. Give it back now. */
+            xSemaphoreGive( xTXDescriptorSemaphore );
         }
 
         #if ( ipconfigZERO_COPY_TX_DRIVER != 0 )
         {
-            /* Confirm that the pxDescriptor may be kept by the driver. */
-            bReleaseAfterSend = pdFALSE;
+            if( ulResult == GMAC_OK )
+            {
+                /* The message was send in a zero-copy way.
+                 * It will be released after a successful transmission. */
+                bReleaseAfterSend = pdFALSE;
+            }
         }
         #endif /* ipconfigZERO_COPY_TX_DRIVER */
         /* Not interested in a call-back after TX. */