net: stmmac: fix unbalanced ptp clock issue in suspend/resume flow

Current stmmac driver will prepare/enable ptp_ref clock in
stmmac_init_tstamp_counter().

The stmmac_pltfr_noirq_suspend will disable it once in suspend flow.

But in resume flow,
	stmmac_pltfr_noirq_resume --> stmmac_init_tstamp_counter
	stmmac_resume --> stmmac_hw_setup --> stmmac_init_ptp --> stmmac_init_tstamp_counter
ptp_ref clock reference counter increases twice, which leads to unbalance
ptp clock when resume back.

Move ptp_ref clock prepare/enable out of stmmac_init_tstamp_counter to fix it.

Fixes: 0735e63 ("net: stmmac: skip only stmmac_ptp_register when resume from suspend")
Signed-off-by: Biao Huang <biao.huang@mediatek.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/stmicro/stmmac/stmmac_main.c

@@ -834,19 +834,10 @@ int stmmac_init_tstamp_counter(struct stmmac_priv *priv, u32 systime_flags)
 	struct timespec64 now;
 	u32 sec_inc = 0;
 	u64 temp = 0;
-	int ret;
 
 	if (!(priv->dma_cap.time_stamp || priv->dma_cap.atime_stamp))
 		return -EOPNOTSUPP;
 
-	ret = clk_prepare_enable(priv->plat->clk_ptp_ref);
-	if (ret < 0) {
-		netdev_warn(priv->dev,
-			    "failed to enable PTP reference clock: %pe\n",
-			    ERR_PTR(ret));
-		return ret;
-	}
-
 	stmmac_config_hw_tstamping(priv, priv->ptpaddr, systime_flags);
 	priv->systime_flags = systime_flags;
 
@@ -3270,6 +3261,14 @@ static int stmmac_hw_setup(struct net_device *dev, bool ptp_register)
 
 	stmmac_mmc_setup(priv);
 
+	if (ptp_register) {
+		ret = clk_prepare_enable(priv->plat->clk_ptp_ref);
+		if (ret < 0)
+			netdev_warn(priv->dev,
+				    "failed to enable PTP reference clock: %pe\n",
+				    ERR_PTR(ret));
+	}
+
 	ret = stmmac_init_ptp(priv);
 	if (ret == -EOPNOTSUPP)
 		netdev_info(priv->dev, "PTP not supported by HW\n");

drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c

@@ -815,7 +815,13 @@ static int __maybe_unused stmmac_pltfr_noirq_resume(struct device *dev)
 		if (ret)
 			return ret;
 
-		stmmac_init_tstamp_counter(priv, priv->systime_flags);
+		ret = clk_prepare_enable(priv->plat->clk_ptp_ref);
+		if (ret < 0) {
+			netdev_warn(priv->dev,
+				    "failed to enable PTP reference clock: %pe\n",
+				    ERR_PTR(ret));
+			return ret;
+		}
 	}
 
 	return 0;