r8169: improve statistics of missed rx packets

Register RxMissed exists on few early chip versions only, however all
chip versions have the number of missed RX packets in the hardware
counters. Therefore remove using RxMissed and get the number of missed
RX packets from the hardware stats.
Signed-off-by: NHeiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/realtek/r8169_main.c

@@ -212,7 +212,6 @@ enum rtl_registers {
 					/* Unlimited maximum PCI burst. */
 #define	RX_DMA_BURST			(7 << RXCFG_DMA_SHIFT)
 
-	RxMissed	= 0x4c,
 	Cfg9346		= 0x50,
 	Config0		= 0x51,
 	Config1		= 0x52,
@@ -576,6 +575,7 @@ struct rtl8169_tc_offsets {
 	__le64	tx_errors;
 	__le32	tx_multi_collision;
 	__le16	tx_aborted;
+	__le16	rx_missed;
 };
 
 enum rtl_flag {
@@ -1690,6 +1690,7 @@ static bool rtl8169_init_counter_offsets(struct rtl8169_private *tp)
 	tp->tc_offset.tx_errors = counters->tx_errors;
 	tp->tc_offset.tx_multi_collision = counters->tx_multi_collision;
 	tp->tc_offset.tx_aborted = counters->tx_aborted;
+	tp->tc_offset.rx_missed = counters->rx_missed;
 	tp->tc_offset.inited = true;
 
 	return ret;
@@ -3837,8 +3838,6 @@ static void rtl_hw_start_8169(struct rtl8169_private *tp)
 
 	rtl8169_set_magic_reg(tp, tp->mac_version);
 
-	RTL_W32(tp, RxMissed, 0);
-
 	/* disable interrupt coalescing */
 	RTL_W16(tp, IntrMitigate, 0x0000);
 }
@@ -4681,17 +4680,6 @@ static int rtl8169_poll(struct napi_struct *napi, int budget)
 	return work_done;
 }
 
-static void rtl8169_rx_missed(struct net_device *dev)
-{
-	struct rtl8169_private *tp = netdev_priv(dev);
-
-	if (tp->mac_version > RTL_GIGA_MAC_VER_06)
-		return;
-
-	dev->stats.rx_missed_errors += RTL_R32(tp, RxMissed) & 0xffffff;
-	RTL_W32(tp, RxMissed, 0);
-}
-
 static void r8169_phylink_handler(struct net_device *ndev)
 {
 	struct rtl8169_private *tp = netdev_priv(ndev);
@@ -4741,12 +4729,6 @@ static void rtl8169_down(struct net_device *dev)
 	netif_stop_queue(dev);
 
 	rtl8169_hw_reset(tp);
-	/*
-	 * At this point device interrupts can not be enabled in any function,
-	 * as netif_running is not true (rtl8169_interrupt, rtl8169_reset_task)
-	 * and napi is disabled (rtl8169_poll).
-	 */
-	rtl8169_rx_missed(dev);
 
 	/* Give a racing hard_start_xmit a few cycles to complete. */
 	synchronize_rcu();
@@ -4891,9 +4873,6 @@ rtl8169_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
 
 	pm_runtime_get_noresume(&pdev->dev);
 
-	if (netif_running(dev) && pm_runtime_active(&pdev->dev))
-		rtl8169_rx_missed(dev);
-
 	do {
 		start = u64_stats_fetch_begin_irq(&tp->rx_stats.syncp);
 		stats->rx_packets = tp->rx_stats.packets;
@@ -4912,7 +4891,6 @@ rtl8169_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
 	stats->rx_errors	= dev->stats.rx_errors;
 	stats->rx_crc_errors	= dev->stats.rx_crc_errors;
 	stats->rx_fifo_errors	= dev->stats.rx_fifo_errors;
-	stats->rx_missed_errors = dev->stats.rx_missed_errors;
 	stats->multicast	= dev->stats.multicast;
 
 	/*
@@ -4932,6 +4910,8 @@ rtl8169_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
 		le32_to_cpu(tp->tc_offset.tx_multi_collision);
 	stats->tx_aborted_errors = le16_to_cpu(counters->tx_aborted) -
 		le16_to_cpu(tp->tc_offset.tx_aborted);
+	stats->rx_missed_errors = le16_to_cpu(counters->rx_missed) -
+		le16_to_cpu(tp->tc_offset.rx_missed);
 
 	pm_runtime_put_noidle(&pdev->dev);
 }
@@ -5017,7 +4997,6 @@ static int rtl8169_runtime_suspend(struct device *device)
 	rtl8169_net_suspend(dev);
 
 	/* Update counters before going runtime suspend */
-	rtl8169_rx_missed(dev);
 	rtl8169_update_counters(tp);
 
 	return 0;