Merge tag 'linux-can-fixes-for-4.16-20180314' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can

Marc Kleine-Budde says:

====================
pull-request: can 2018-03-14

this is a pull request of two patches for net/master.

Both patches are by Andri Yngvason and fix problems in the cc770 driver,
that show up quite fast on RT systems, but also on non RT setups.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/can/cc770/cc770.c

@@ -390,37 +390,23 @@ static int cc770_get_berr_counter(const struct net_device *dev,
 	return 0;
 }
 
-static netdev_tx_t cc770_start_xmit(struct sk_buff *skb, struct net_device *dev)
+static void cc770_tx(struct net_device *dev, int mo)
 {
 	struct cc770_priv *priv = netdev_priv(dev);
-	struct net_device_stats *stats = &dev->stats;
-	struct can_frame *cf = (struct can_frame *)skb->data;
-	unsigned int mo = obj2msgobj(CC770_OBJ_TX);
+	struct can_frame *cf = (struct can_frame *)priv->tx_skb->data;
 	u8 dlc, rtr;
 	u32 id;
 	int i;
 
-	if (can_dropped_invalid_skb(dev, skb))
-		return NETDEV_TX_OK;
-
-	if ((cc770_read_reg(priv,
-			    msgobj[mo].ctrl1) & TXRQST_UNC) == TXRQST_SET) {
-		netdev_err(dev, "TX register is still occupied!\n");
-		return NETDEV_TX_BUSY;
-	}
-
-	netif_stop_queue(dev);
-
 	dlc = cf->can_dlc;
 	id = cf->can_id;
-	if (cf->can_id & CAN_RTR_FLAG)
-		rtr = 0;
-	else
-		rtr = MSGCFG_DIR;
+	rtr = cf->can_id & CAN_RTR_FLAG ? 0 : MSGCFG_DIR;
+
+	cc770_write_reg(priv, msgobj[mo].ctrl0,
+			MSGVAL_RES | TXIE_RES | RXIE_RES | INTPND_RES);
 	cc770_write_reg(priv, msgobj[mo].ctrl1,
 			RMTPND_RES | TXRQST_RES | CPUUPD_SET | NEWDAT_RES);
-	cc770_write_reg(priv, msgobj[mo].ctrl0,
-			MSGVAL_SET | TXIE_SET | RXIE_RES | INTPND_RES);
+
 	if (id & CAN_EFF_FLAG) {
 		id &= CAN_EFF_MASK;
 		cc770_write_reg(priv, msgobj[mo].config,
@@ -439,22 +425,30 @@ static netdev_tx_t cc770_start_xmit(struct sk_buff *skb, struct net_device *dev)
 	for (i = 0; i < dlc; i++)
 		cc770_write_reg(priv, msgobj[mo].data[i], cf->data[i]);
 
-	/* Store echo skb before starting the transfer */
-	can_put_echo_skb(skb, dev, 0);
-
 	cc770_write_reg(priv, msgobj[mo].ctrl1,
-			RMTPND_RES | TXRQST_SET | CPUUPD_RES | NEWDAT_UNC);
+			RMTPND_UNC | TXRQST_SET | CPUUPD_RES | NEWDAT_UNC);
+	cc770_write_reg(priv, msgobj[mo].ctrl0,
+			MSGVAL_SET | TXIE_SET | RXIE_SET | INTPND_UNC);
+}
 
-	stats->tx_bytes += dlc;
+static netdev_tx_t cc770_start_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+	struct cc770_priv *priv = netdev_priv(dev);
+	unsigned int mo = obj2msgobj(CC770_OBJ_TX);
 
+	if (can_dropped_invalid_skb(dev, skb))
+		return NETDEV_TX_OK;
 
-	/*
-	 * HM: We had some cases of repeated IRQs so make sure the
-	 * INT is acknowledged I know it's already further up, but
-	 * doing again fixed the issue
-	 */
-	cc770_write_reg(priv, msgobj[mo].ctrl0,
-			MSGVAL_UNC | TXIE_UNC | RXIE_UNC | INTPND_RES);
+	netif_stop_queue(dev);
+
+	if ((cc770_read_reg(priv,
+			    msgobj[mo].ctrl1) & TXRQST_UNC) == TXRQST_SET) {
+		netdev_err(dev, "TX register is still occupied!\n");
+		return NETDEV_TX_BUSY;
+	}
+
+	priv->tx_skb = skb;
+	cc770_tx(dev, mo);
 
 	return NETDEV_TX_OK;
 }
@@ -680,19 +674,47 @@ static void cc770_tx_interrupt(struct net_device *dev, unsigned int o)
 	struct cc770_priv *priv = netdev_priv(dev);
 	struct net_device_stats *stats = &dev->stats;
 	unsigned int mo = obj2msgobj(o);
+	struct can_frame *cf;
+	u8 ctrl1;
+
+	ctrl1 = cc770_read_reg(priv, msgobj[mo].ctrl1);
 
-	/* Nothing more to send, switch off interrupts */
 	cc770_write_reg(priv, msgobj[mo].ctrl0,
 			MSGVAL_RES | TXIE_RES | RXIE_RES | INTPND_RES);
-	/*
-	 * We had some cases of repeated IRQ so make sure the
-	 * INT is acknowledged
+	cc770_write_reg(priv, msgobj[mo].ctrl1,
+			RMTPND_RES | TXRQST_RES | MSGLST_RES | NEWDAT_RES);
+
+	if (unlikely(!priv->tx_skb)) {
+		netdev_err(dev, "missing tx skb in tx interrupt\n");
+		return;
+	}
+
+	if (unlikely(ctrl1 & MSGLST_SET)) {
+		stats->rx_over_errors++;
+		stats->rx_errors++;
+	}
+
+	/* When the CC770 is sending an RTR message and it receives a regular
+	 * message that matches the id of the RTR message, it will overwrite the
+	 * outgoing message in the TX register. When this happens we must
+	 * process the received message and try to transmit the outgoing skb
+	 * again.
 	 */
-	cc770_write_reg(priv, msgobj[mo].ctrl0,
-			MSGVAL_UNC | TXIE_UNC | RXIE_UNC | INTPND_RES);
+	if (unlikely(ctrl1 & NEWDAT_SET)) {
+		cc770_rx(dev, mo, ctrl1);
+		cc770_tx(dev, mo);
+		return;
+	}
 
-	stats->tx_packets++;
+	can_put_echo_skb(priv->tx_skb, dev, 0);
 	can_get_echo_skb(dev, 0);
+
+	cf = (struct can_frame *)priv->tx_skb->data;
+	stats->tx_bytes += cf->can_dlc;
+	stats->tx_packets++;
+
+	priv->tx_skb = NULL;
+
 	netif_wake_queue(dev);
 }
 
@@ -804,6 +826,7 @@ struct net_device *alloc_cc770dev(int sizeof_priv)
 	priv->can.do_set_bittiming = cc770_set_bittiming;
 	priv->can.do_set_mode = cc770_set_mode;
 	priv->can.ctrlmode_supported = CAN_CTRLMODE_3_SAMPLES;
+	priv->tx_skb = NULL;
 
 	memcpy(priv->obj_flags, cc770_obj_flags, sizeof(cc770_obj_flags));
 

drivers/net/can/cc770/cc770.h

@@ -193,6 +193,8 @@ struct cc770_priv {
 	u8 cpu_interface;	/* CPU interface register */
 	u8 clkout;		/* Clock out register */
 	u8 bus_config;		/* Bus conffiguration register */
+
+	struct sk_buff *tx_skb;
 };
 
 struct net_device *alloc_cc770dev(int sizeof_priv);