[PATCH net v4] smsc911x: only update stats when interface is up

[Wolfram Sang]

Otherwise the clocks are not enabled and reading registers will OOPS.
Copy the behaviour from Renesas SH_ETH and use a custom flag because
using netif_running() is racy. A generic solution still needs to be
implemented. Tested on a Renesas APE6-EK.

Fixes: 1e30b8d755b8 ("net: smsc911x: Make Runtime PM handling more fine-grained")
Signed-off-by: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
---

Changes since v3:
* broken out of a patch series
* don't use netif_running() but a custom flag

 drivers/net/ethernet/smsc/smsc911x.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/smsc/smsc911x.c b/drivers/net/ethernet/smsc/smsc911x.c
index a690d139e177..af96986cbc88 100644
--- a/drivers/net/ethernet/smsc/smsc911x.c
+++ b/drivers/net/ethernet/smsc/smsc911x.c
@@ -140,6 +140,8 @@ struct smsc911x_data {
 
 	/* clock */
 	struct clk *clk;
+
+	bool is_open;
 };
 
 /* Easy access to information */
@@ -1738,6 +1740,8 @@ static int smsc911x_open(struct net_device *dev)
 	smsc911x_reg_write(pdata, TX_CFG, TX_CFG_TX_ON_);
 
 	netif_start_queue(dev);
+	pdata->is_open = true;
+
 	return 0;
 
 irq_stop_out:
@@ -1778,6 +1782,8 @@ static int smsc911x_stop(struct net_device *dev)
 		dev->phydev = NULL;
 	}
 	netif_carrier_off(dev);
+	pdata->is_open = false;
+
 	pm_runtime_put(dev->dev.parent);
 
 	SMSC_TRACE(pdata, ifdown, "Interface stopped");
@@ -1841,8 +1847,12 @@ smsc911x_hard_start_xmit(struct sk_buff *skb, struct net_device *dev)
 static struct net_device_stats *smsc911x_get_stats(struct net_device *dev)
 {
 	struct smsc911x_data *pdata = netdev_priv(dev);
-	smsc911x_tx_update_txcounters(dev);
-	dev->stats.rx_dropped += smsc911x_reg_read(pdata, RX_DROP);
+
+	if (pdata->is_open) {
+		smsc911x_tx_update_txcounters(dev);
+		dev->stats.rx_dropped += smsc911x_reg_read(pdata, RX_DROP);
+	}
+
 	return &dev->stats;
 }
 
-- 
2.30.2