2 files changed, 61 insertions, 23 deletions

diff --git a/drivers/net/can/spi/hi311x.c b/drivers/net/can/spi/hi311x.c
index 148d974ebb21..09ae218315d7 100644
--- a/drivers/net/can/spi/hi311x.c
+++ b/drivers/net/can/spi/hi311x.c
@@ -663,27 +663,27 @@ static irqreturn_t hi3110_can_ist(int irq, void *dev_id)
 			u8 rxerr, txerr;
 
 			skb = alloc_can_err_skb(net, &cf);
-			if (!skb)
-				break;
 
 			txerr = hi3110_read(spi, HI3110_READ_TEC);
 			rxerr = hi3110_read(spi, HI3110_READ_REC);
 			tx_state = txerr >= rxerr ? new_state : 0;
 			rx_state = txerr <= rxerr ? new_state : 0;
 			can_change_state(net, cf, tx_state, rx_state);
-			netif_rx(skb);
 
 			if (new_state == CAN_STATE_BUS_OFF) {
+				if (skb)
+					netif_rx(skb);
 				can_bus_off(net);
 				if (priv->can.restart_ms == 0) {
 					priv->force_quit = 1;
 					hi3110_hw_sleep(spi);
 					break;
 				}
-			} else {
+			} else if (skb) {
 				cf->can_id |= CAN_ERR_CNT;
 				cf->data[6] = txerr;
 				cf->data[7] = rxerr;
+				netif_rx(skb);
 			}
 		}
 
@@ -696,27 +696,38 @@ static irqreturn_t hi3110_can_ist(int irq, void *dev_id)
 			/* Check for protocol errors */
 			if (eflag & HI3110_ERR_PROTOCOL_MASK) {
 				skb = alloc_can_err_skb(net, &cf);
-				if (!skb)
-					break;
+				if (skb)
+					cf->can_id |= CAN_ERR_PROT | CAN_ERR_BUSERROR;
 
-				cf->can_id |= CAN_ERR_PROT | CAN_ERR_BUSERROR;
 				priv->can.can_stats.bus_error++;
-				priv->net->stats.rx_errors++;
-				if (eflag & HI3110_ERR_BITERR)
-					cf->data[2] |= CAN_ERR_PROT_BIT;
-				else if (eflag & HI3110_ERR_FRMERR)
-					cf->data[2] |= CAN_ERR_PROT_FORM;
-				else if (eflag & HI3110_ERR_STUFERR)
-					cf->data[2] |= CAN_ERR_PROT_STUFF;
-				else if (eflag & HI3110_ERR_CRCERR)
-					cf->data[3] |= CAN_ERR_PROT_LOC_CRC_SEQ;
-				else if (eflag & HI3110_ERR_ACKERR)
-					cf->data[3] |= CAN_ERR_PROT_LOC_ACK;
-
-				cf->data[6] = hi3110_read(spi, HI3110_READ_TEC);
-				cf->data[7] = hi3110_read(spi, HI3110_READ_REC);
+				if (eflag & HI3110_ERR_BITERR) {
+					priv->net->stats.tx_errors++;
+					if (skb)
+						cf->data[2] |= CAN_ERR_PROT_BIT;
+				} else if (eflag & HI3110_ERR_FRMERR) {
+					priv->net->stats.rx_errors++;
+					if (skb)
+						cf->data[2] |= CAN_ERR_PROT_FORM;
+				} else if (eflag & HI3110_ERR_STUFERR) {
+					priv->net->stats.rx_errors++;
+					if (skb)
+						cf->data[2] |= CAN_ERR_PROT_STUFF;
+				} else if (eflag & HI3110_ERR_CRCERR) {
+					priv->net->stats.rx_errors++;
+					if (skb)
+						cf->data[3] |= CAN_ERR_PROT_LOC_CRC_SEQ;
+				} else if (eflag & HI3110_ERR_ACKERR) {
+					priv->net->stats.tx_errors++;
+					if (skb)
+						cf->data[3] |= CAN_ERR_PROT_LOC_ACK;
+				}
+
 				netdev_dbg(priv->net, "Bus Error\n");
-				netif_rx(skb);
+				if (skb) {
+					cf->data[6] = hi3110_read(spi, HI3110_READ_TEC);
+					cf->data[7] = hi3110_read(spi, HI3110_READ_REC);
+					netif_rx(skb);
+				}
 			}
 		}
 
diff --git a/drivers/net/can/spi/mcp251xfd/mcp251xfd-tef.c b/drivers/net/can/spi/mcp251xfd/mcp251xfd-tef.c
index d3ac865933fd..e94321849fd7 100644
--- a/drivers/net/can/spi/mcp251xfd/mcp251xfd-tef.c
+++ b/drivers/net/can/spi/mcp251xfd/mcp251xfd-tef.c
@@ -21,6 +21,11 @@ static inline bool mcp251xfd_tx_fifo_sta_empty(u32 fifo_sta)
 	return fifo_sta & MCP251XFD_REG_FIFOSTA_TFERFFIF;
 }
 
+static inline bool mcp251xfd_tx_fifo_sta_less_than_half_full(u32 fifo_sta)
+{
+	return fifo_sta & MCP251XFD_REG_FIFOSTA_TFHRFHIF;
+}
+
 static inline int
 mcp251xfd_tef_tail_get_from_chip(const struct mcp251xfd_priv *priv,
 				 u8 *tef_tail)
@@ -147,7 +152,29 @@ mcp251xfd_get_tef_len(struct mcp251xfd_priv *priv, u8 *len_p)
 	BUILD_BUG_ON(sizeof(tx_ring->obj_num) != sizeof(len));
 
 	len = (chip_tx_tail << shift) - (tail << shift);
-	*len_p = len >> shift;
+	len >>= shift;
+
+	/* According to mcp2518fd erratum DS80000789E 6. the FIFOCI
+	 * bits of a FIFOSTA register, here the TX-FIFO tail index
+	 * might be corrupted.
+	 *
+	 * However here it seems the bit indicating that the TX-FIFO
+	 * is empty (MCP251XFD_REG_FIFOSTA_TFERFFIF) is not correct
+	 * while the TX-FIFO tail index is.
+	 *
+	 * We assume the TX-FIFO is empty, i.e. all pending CAN frames
+	 * haven been send, if:
+	 * - Chip's head and tail index are equal (len == 0).
+	 * - The TX-FIFO is less than half full.
+	 *   (The TX-FIFO empty case has already been checked at the
+	 *    beginning of this function.)
+	 * - No free buffers in the TX ring.
+	 */
+	if (len == 0 && mcp251xfd_tx_fifo_sta_less_than_half_full(fifo_sta) &&
+	    mcp251xfd_get_tx_free(tx_ring) == 0)
+		len = tx_ring->obj_num;
+
+	*len_p = len;
 
 	return 0;
 }