[PATCH net-next] net: ethtool: allow MAC drivers to override ethtool get_ts_info

[Russell King <rmk+kernel@armlinux.org.uk>]

Check whether the MAC driver has implemented the get_ts_info()
method first, and call it if present.  If this method returns
-EOPNOTSUPP, defer to the phylib or default implementation.

This allows network drivers such as mvpp2 to use their more accurate
timestamping implementation than using a less accurate implementation
in the PHY. Network drivers can opt to defer to phylib by returning
-EOPNOTSUPP.

This change will be needed if the Marvell PHY drivers add support for
PTP.

Note: this may cause a change for any drivers that use phylib and
provide get_ts_info(). It is not obvious if any such cases exist.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
---
 net/ethtool/common.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/net/ethtool/common.c b/net/ethtool/common.c
index 24036e3055a1..9ec93e24f239 100644
--- a/net/ethtool/common.c
+++ b/net/ethtool/common.c
@@ -385,14 +385,18 @@ int __ethtool_get_ts_info(struct net_device *dev, struct ethtool_ts_info *info)
 {
 	const struct ethtool_ops *ops = dev->ethtool_ops;
 	struct phy_device *phydev = dev->phydev;
+	int ret;
 
 	memset(info, 0, sizeof(*info));
 	info->cmd = ETHTOOL_GET_TS_INFO;
 
+	if (ops->get_ts_info) {
+		ret = ops->get_ts_info(dev, info);
+		if (ret != -EOPNOTSUPP)
+			return ret;
+	}
 	if (phy_has_tsinfo(phydev))
 		return phy_ts_info(phydev, info);
-	if (ops->get_ts_info)
-		return ops->get_ts_info(dev, info);
 
 	info->so_timestamping = SOF_TIMESTAMPING_RX_SOFTWARE |
 				SOF_TIMESTAMPING_SOFTWARE;
-- 
2.20.1