arch/arm/src/sam34 and sama5: Port Anthony Merlino's fix of commit ee840c74da to similar Ethernet drivers for parts in other SAM families.

arch/arm/src/sam34/sam_emac.c

@@ -1,7 +1,7 @@
 /****************************************************************************
  * arch/arm/src/sam34/sam_emac.c
  *
- *   Copyright (C) 2014-2015, 2017-2018 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2014-2015, 2017-2019 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * This logic derives from the SAM34D3 Ethernet driver.
@@ -1163,9 +1163,23 @@ static int sam_recvframe(struct sam_emac_s *priv)
                           (uintptr_t)rxdesc + sizeof(struct emac_rxdesc_s));
     }
 
-  /* No packet was found */
+  /* isframe indicates that we have found a SOF. If we've received a SOF,
+   * but not an EOF in the sequential buffers we own, it must mean that we
+   * have a partial packet. This should only happen if there was a Buffer
+   * Not Available (BNA) error.  When bursts of data come in, quickly
+   * filling the available buffers, before our interrupts can even service
+   * them. Eventually, the ring buffer loops back on itself and the
+   * peripheral sees it cannot write the next fragment of the packet.
+   *
+   * In this case, we keep the rxndx at the start of the last frame, since
+   * the peripheral will finish writing the packet there next.
+   */
 
+  if (!isframe)
+    {
       priv->rxndx = rxndx;
+    }
+
   ninfo("rxndx: %d\n", priv->rxndx);
   return -EAGAIN;
 }

arch/arm/src/sama5/sam_emaca.c

@@ -4,7 +4,7 @@
  * 10/100 Base-T Ethernet driver for the SAMA5D3.  Denoted as 'A' to
  * distinguish it from the SAMA5D4 EMAC driver.
  *
- *   Copyright (C) 2013-2018 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2013-2019 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * References:
@@ -1201,9 +1201,23 @@ static int sam_recvframe(struct sam_emac_s *priv)
                              (uintptr_t)rxdesc + sizeof(struct emac_rxdesc_s));
     }
 
-  /* No packet was found */
+  /* isframe indicates that we have found a SOF. If we've received a SOF,
+   * but not an EOF in the sequential buffers we own, it must mean that we
+   * have a partial packet. This should only happen if there was a Buffer
+   * Not Available (BNA) error.  When bursts of data come in, quickly
+   * filling the available buffers, before our interrupts can even service
+   * them. Eventually, the ring buffer loops back on itself and the
+   * peripheral sees it cannot write the next fragment of the packet.
+   *
+   * In this case, we keep the rxndx at the start of the last frame, since
+   * the peripheral will finish writing the packet there next.
+   */
 
+  if (!isframe)
+    {
       priv->rxndx = rxndx;
+    }
+
   ninfo("rxndx: %d\n", priv->rxndx);
   return -EAGAIN;
 }

arch/arm/src/sama5/sam_emacb.c

@@ -8,7 +8,7 @@
  * separate (mostly because the 'B' driver needs to support two EMAC blocks.
  * But the 'B' driver should replace the 'A' driver someday.
  *
- *   Copyright (C) 2014-2015, 2017-2018 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2014-2015, 2017-2019 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * This logic derives from the SAM4E Ethernet driver which, in turn, derived
@@ -1536,9 +1536,23 @@ static int sam_recvframe(struct sam_emac_s *priv)
                              (uintptr_t)rxdesc + sizeof(struct emac_rxdesc_s));
     }
 
-  /* No packet was found */
+  /* isframe indicates that we have found a SOF. If we've received a SOF,
+   * but not an EOF in the sequential buffers we own, it must mean that we
+   * have a partial packet. This should only happen if there was a Buffer
+   * Not Available (BNA) error.  When bursts of data come in, quickly
+   * filling the available buffers, before our interrupts can even service
+   * them. Eventually, the ring buffer loops back on itself and the
+   * peripheral sees it cannot write the next fragment of the packet.
+   *
+   * In this case, we keep the rxndx at the start of the last frame, since
+   * the peripheral will finish writing the packet there next.
+   */
 
+  if (!isframe)
+    {
       priv->rxndx = rxndx;
+    }
+
   ninfo("rxndx: %d\n", priv->rxndx);
   return -EAGAIN;
 }

arch/arm/src/sama5/sam_gmac.c

@@ -1,7 +1,7 @@
 /****************************************************************************
  * arch/arm/src/sama5/sam_gmac.c
  *
- *   Copyright (C) 2013-2018 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2013-2019 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * References:
@@ -1131,9 +1131,23 @@ static int sam_recvframe(struct sam_gmac_s *priv)
                              (uintptr_t)rxdesc + sizeof(struct gmac_rxdesc_s));
     }
 
-  /* No packet was found */
+  /* isframe indicates that we have found a SOF. If we've received a SOF,
+   * but not an EOF in the sequential buffers we own, it must mean that we
+   * have a partial packet. This should only happen if there was a Buffer
+   * Not Available (BNA) error.  When bursts of data come in, quickly
+   * filling the available buffers, before our interrupts can even service
+   * them. Eventually, the ring buffer loops back on itself and the
+   * peripheral sees it cannot write the next fragment of the packet.
+   *
+   * In this case, we keep the rxndx at the start of the last frame, since
+   * the peripheral will finish writing the packet there next.
+   */
 
+  if (!isframe)
+    {
       priv->rxndx = rxndx;
+    }
+
   ninfo("rxndx: %d\n", priv->rxndx);
   return -EAGAIN;
 }

arch/arm/src/samv7/sam_emac.c

@@ -1873,16 +1873,16 @@ static int sam_recvframe(struct sam_emac_s *priv, int qid)
                              (uintptr_t)rxdesc + sizeof(struct emac_rxdesc_s));
     }
 
-  /* isframe indicates that we have found a SOF. If we've received a SOF, but not
+  /* isframe indicates that we have found a SOF. If we've received a SOF,
-   * an EOF in the sequential buffers we own, it must mean that we have a partial
+   * but not an EOF in the sequential buffers we own, it must mean that we
-   * packet. This should only happen if there was a Buffer Not Available (BNA) error.
+   * have a partial packet. This should only happen if there was a Buffer
-   * When bursts of data come in, quickly filling the available buffers, before our
+   * Not Available (BNA) error.  When bursts of data come in, quickly
-   * interrupts can even service them. Eventually, the ring buffer loops back on
+   * filling the available buffers, before our interrupts can even service
-   * itself and the peripheral sees it cannot write the next fragment of the packet.
+   * them. Eventually, the ring buffer loops back on itself and the
-   *
+   * peripheral sees it cannot write the next fragment of the packet.
-   * In this case, we keep the rxndx at the start of the last frame, since the peripheral
-   * will finish writing the packet there next.
    *
+   * In this case, we keep the rxndx at the start of the last frame, since
+   * the peripheral will finish writing the packet there next.
    */
 
   if (!isframe)