[PATCH net-next] net: stmmac: mask the MAC interrupt while resume resets the MAC

[Igor Velkov via B4 Relay]

From: Igor Velkov <iav@xxxxxx>

stmmac_resume() resets the MAC in stmmac_hw_setup(). On dwmac1000 the
reset clears the interrupt mask, and all core interrupts stay unmasked
until dwmac1000_core_init() writes it again. A link change in that
window raises an RGMII interrupt, and no handler clears it since
commit 2e2c878a3141 ("net: stmmac: remove SGMII/RGMII/SMII interrupt handling").
The line storms:

  dwmac_dma_interrupt: unexpected status 04000000

The message repeats every few milliseconds and the network stays down
until a power cycle or a watchdog reset. A register dump at the first
message on ODROID-HC4 showed the pending link change with a zero mask:

  core int_status 00000001 int_mask 00000000 pmt 00000000 rgsmiiis 0000000d

Disable the interrupt line for the whole resume and enable it again on
every exit path. The line is IRQF_SHARED, so leave it enabled during
suspend, where another user of the line may wake the system.

Wake-on-LAN resume on two boards:
- ODROID-HC4 (dwmac-meson8b, 7.2): the storm on resume, none in 5
  resumes with this patch.
- Helios64 (dwmac-rk, 7.3-rc5): the storm in 2 of 3 resumes, none in
  26 resumes with this patch.

Assisted-by: LLM
Signed-off-by: Igor Velkov <iav@xxxxxx>
---
Ported to net-next, where stmmac_resume() gained error labels. Tested
on hardware with 7.2 and 7.3-rc5; build-tested on net-next.
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 24 ++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 3ad9252bf6ae..6e0415538327 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -8356,16 +8356,26 @@ int stmmac_resume(struct device *dev)
 {
 	struct net_device *ndev = dev_get_drvdata(dev);
 	struct stmmac_priv *priv = netdev_priv(ndev);
+	bool irq_off;
 	int ret;
 
+	/* Resume resets the MAC, leaving every core interrupt unmasked until
+	 * the mask is written again: a link change in that window would storm.
+	 */
+	irq_off = netif_running(ndev);
+	if (irq_off)
+		disable_irq(ndev->irq);
+
 	if (priv->plat->resume) {
 		ret = priv->plat->resume(dev, priv->plat->bsp_priv);
 		if (ret)
-			return ret;
+			goto out;
 	}
 
-	if (!netif_running(ndev))
-		return 0;
+	if (!netif_running(ndev)) {
+		ret = 0;
+		goto out;
+	}
 
 	/* Power Down bit, into the PM register, is cleared
 	 * automatically as soon as a magic packet or a Wake-up frame
@@ -8388,7 +8398,7 @@ int stmmac_resume(struct device *dev)
 	if (!(priv->plat->flags & STMMAC_FLAG_SERDES_UP_AFTER_PHY_LINKUP)) {
 		ret = stmmac_legacy_serdes_power_up(priv);
 		if (ret < 0)
-			return ret;
+			goto out;
 	}
 
 	rtnl_lock();
@@ -8442,7 +8452,8 @@ int stmmac_resume(struct device *dev)
 
 	netif_device_attach(ndev);
 
-	return 0;
+	ret = 0;
+	goto out;
 
 error_stop_dma:
 	stmmac_stop_all_dma(priv);
@@ -8451,6 +8462,9 @@ int stmmac_resume(struct device *dev)
 	stmmac_legacy_serdes_power_down(priv);
 	mutex_unlock(&priv->lock);
 	rtnl_unlock();
+out:
+	if (irq_off)
+		enable_irq(ndev->irq);
 
 	return ret;
 }

---
base-commit: 47a1446725732cd3996edf607e8739334bbf4d78
change-id: 20260930-stmmac-irq-shut-03bac57ae0bb

Best regards,
-- 
Igor Velkov <iav@xxxxxx>