[PATCH net] net: stmmac: propagate PTP init failures in __stmmac_open() and stmmac_resume()

[Lorenzo Bianconi]

stmmac_setup_ptp() returns void and swallows both PTP setup errors:
the PTP reference clock enable and stmmac_init_timestamping()
failures are logged but never propagated. When they fail, the MAC
system time counter is left in its post-reset, non-running state,
while the driver keeps operating as if timestamping were up.
This matters for TAPRIO/EST qdisc offloading, which derives the EST
base time from the hardware timestamp counter: arming the gate list
against a non-advancing time base would leave the schedule permanently
stuck. Make stmmac_setup_ptp() return an error code.

Fixes: 92ba6888510c ("stmmac: add the support for PTP hw clock driver")
Fixes: 0ad2be79f254 ("net: stmmac: Balance PTP reference clock enable/disable")
Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi at oss.qualcomm.com>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 66 ++++++++++++++++-------
 1 file changed, 48 insertions(+), 18 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 24656b35350b..d33c82bd3ee4 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -885,6 +885,11 @@ static int stmmac_init_tstamp_counter(struct stmmac_priv *priv,
 	return 0;
 }
 
+static bool stmmac_check_timestamp_cap(struct stmmac_priv *priv)
+{
+	return priv->dma_cap.time_stamp || priv->dma_cap.atime_stamp;
+}
+
 /**
  * stmmac_init_timestamping - initialise timestamping
  * @priv: driver private structure
@@ -900,11 +905,6 @@ static int stmmac_init_timestamping(struct stmmac_priv *priv)
 	if (priv->plat->ptp_clk_freq_config)
 		priv->plat->ptp_clk_freq_config(priv);
 
-	if (!(priv->dma_cap.time_stamp || priv->dma_cap.atime_stamp)) {
-		netdev_info(priv->dev, "PTP not supported by HW\n");
-		return -EOPNOTSUPP;
-	}
-
 	ret = stmmac_init_tstamp_counter(priv, STMMAC_HWTS_ACTIVE |
 					       PTP_TCR_TSCFUPDT);
 	if (ret) {
@@ -937,22 +937,39 @@ static int stmmac_init_timestamping(struct stmmac_priv *priv)
 	return 0;
 }
 
-static void stmmac_setup_ptp(struct stmmac_priv *priv)
+static int stmmac_setup_ptp(struct stmmac_priv *priv)
 {
 	int ret;
 
+	if (!stmmac_check_timestamp_cap(priv)) {
+		netdev_info(priv->dev, "PTP not supported by HW\n");
+		return 0;
+	}
+
 	ret = clk_prepare_enable(priv->plat->clk_ptp_ref);
-	if (ret < 0)
+	if (ret < 0) {
 		netdev_warn(priv->dev,
 			    "failed to enable PTP reference clock: %pe\n",
 			    ERR_PTR(ret));
+		return ret;
+	}
+
+	ret = stmmac_init_timestamping(priv);
+	if (ret) {
+		clk_disable_unprepare(priv->plat->clk_ptp_ref);
+		return ret;
+	}
 
-	if (stmmac_init_timestamping(priv) == 0)
-		stmmac_ptp_register(priv);
+	stmmac_ptp_register(priv);
+
+	return 0;
 }
 
 static void stmmac_release_ptp(struct stmmac_priv *priv)
 {
+	if (!stmmac_check_timestamp_cap(priv))
+		return;
+
 	stmmac_ptp_unregister(priv);
 	clk_disable_unprepare(priv->plat->clk_ptp_ref);
 }
@@ -4161,10 +4178,12 @@ static int __stmmac_open(struct net_device *dev,
 	ret = stmmac_hw_setup(dev);
 	if (ret < 0) {
 		netdev_err(priv->dev, "%s: Hw setup failed\n", __func__);
-		goto init_error;
+		return ret;
 	}
 
-	stmmac_setup_ptp(priv);
+	ret = stmmac_setup_ptp(priv);
+	if (ret)
+		goto ptp_error;
 
 	stmmac_init_coalesce(priv);
 
@@ -4187,9 +4206,10 @@ static int __stmmac_open(struct net_device *dev,
 
 	for (chan = 0; chan < priv->plat->tx_queues_to_use; chan++)
 		hrtimer_cancel(&priv->dma_conf.tx_queue[chan].txtimer);
-
 	stmmac_release_ptp(priv);
-init_error:
+ptp_error:
+	stmmac_stop_all_dma(priv);
+
 	return ret;
 }
 
@@ -8326,13 +8346,14 @@ int stmmac_resume(struct device *dev)
 	ret = stmmac_hw_setup(ndev);
 	if (ret < 0) {
 		netdev_err(priv->dev, "%s: Hw setup failed\n", __func__);
-		stmmac_legacy_serdes_power_down(priv);
-		mutex_unlock(&priv->lock);
-		rtnl_unlock();
-		return ret;
+		goto error_unlock;
 	}
 
-	stmmac_init_timestamping(priv);
+	if (stmmac_check_timestamp_cap(priv)) {
+		ret = stmmac_init_timestamping(priv);
+		if (ret)
+			goto error_stop_dma;
+	}
 
 	stmmac_init_coalesce(priv);
 	phylink_rx_clk_stop_block(priv->phylink);
@@ -8356,6 +8377,15 @@ int stmmac_resume(struct device *dev)
 	netif_device_attach(ndev);
 
 	return 0;
+
+error_stop_dma:
+	stmmac_stop_all_dma(priv);
+error_unlock:
+	stmmac_legacy_serdes_power_down(priv);
+	mutex_unlock(&priv->lock);
+	rtnl_unlock();
+
+	return ret;
 }
 EXPORT_SYMBOL_GPL(stmmac_resume);
 

---
base-commit: 641d03105cc0d2437e32fdeec164f91a4ccef6c4
change-id: 20260904-stmmac-ptp-error-propagate-6c0147b4ce29

Best regards,
-- 
Lorenzo Bianconi <lorenzo.bianconi at oss.qualcomm.com>