[PATCH net-next] net: stmmac: fix timestamping configuration after suspend/resume

["Russell King (Oracle)" <rmk+kernel@armlinux.org.uk>]

When stmmac_init_timestamping() is called, it clears the receive and
transmit path booleans that allow timestamps to be read. These are
never re-initialised until after userspace requests timestamping
features to be enabled.

However, our copy of the timestamp configuration is not cleared, which
means we return the old configuration to userspace when requested.
This is inconsistent. Fix this by clearing the timestamp configuration.

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
---

I'm in two minds whether this should go via net or net-next - no one
has noticed that getting the timestamp configuration after resume
doesn't reflect the hardware state. Here's the commit that introduced
the problem:

Fixes: d6228b7cdd6e ("net: stmmac: implement the SIOCGHWTSTAMP ioctl")

 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 89ded359a9fe..4c127b6b8c08 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -853,6 +853,7 @@ static int stmmac_init_timestamping(struct stmmac_priv *priv)
 		netdev_info(priv->dev,
 			    "IEEE 1588-2008 Advanced Timestamp supported\n");
 
+	memset(&priv->tstamp_config, 0, sizeof(priv->tstamp_config));
 	priv->hwts_tx_en = 0;
 	priv->hwts_rx_en = 0;
 
-- 
2.47.3