[PATCH net v2 03/12] net: au1000: disconnect the PHY before freeing the MDIO bus

[Florian Fainelli <f.fainelli@gmail.com>]

Balance phy_connect() on probe failure and removal. Otherwise PHY
interrupts, device references and the attachment to the freed netdev
survive teardown. Disconnect before unregistering the bus while its MDIO
callbacks and MAC registers remain usable.

PHY teardown can re-enable the MAC for MDIO even if the interface was
never opened. Reset the MAC after PHY and MDIO bus teardown, before
releasing descriptors and register mappings. Skip MAC control accesses
when mac_enabled is clear, since stopping an already clock-gated MAC
hangs MTX-1. Always clear the DMA descriptor control bits and TX state.

The teardown corrections were identified by Sashiko AI review and
hardware testing, with OpenAI Codex assisting implementation, validation
and commit-message consolidation. Previously validated on MTX-1 with
opened and never-opened removal, rebind and traffic; both removal cases
left the MAC enable register at zero. MIPS build and extracted-function
ASan/UBSan checks passed before this series was consolidated.

Fixes: 0638dec01e89 ("[PATCH] net: au1000_eth: PHY framework conversion")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
---
 drivers/net/ethernet/amd/au1000_eth.c | 26 +++++++++++++++++---------
 1 file changed, 17 insertions(+), 9 deletions(-)

diff --git a/drivers/net/ethernet/amd/au1000_eth.c b/drivers/net/ethernet/amd/au1000_eth.c
index 58bc8e1b539d..7063f9e5bc7c 100644
--- a/drivers/net/ethernet/amd/au1000_eth.c
+++ b/drivers/net/ethernet/amd/au1000_eth.c
@@ -584,14 +584,17 @@ static void au1000_reset_mac_unlocked(struct net_device *dev)
 	struct au1000_private *const aup = netdev_priv(dev);
 	int i;
 
-	au1000_hard_stop(dev);
+	if (aup->mac_enabled) {
+		au1000_hard_stop(dev);
 
-	writel(MAC_EN_CLOCK_ENABLE, aup->enable);
-	wmb(); /* drain writebuffer */
-	mdelay(2);
-	writel(0, aup->enable);
-	wmb(); /* drain writebuffer */
-	mdelay(2);
+		writel(MAC_EN_CLOCK_ENABLE, aup->enable);
+		wmb(); /* drain writebuffer */
+		mdelay(2);
+		writel(0, aup->enable);
+		wmb(); /* drain writebuffer */
+		mdelay(2);
+		aup->mac_enabled = 0;
+	}
 
 	aup->tx_full = 0;
 	for (i = 0; i < NUM_RX_DMA; i++) {
@@ -603,8 +606,6 @@ static void au1000_reset_mac_unlocked(struct net_device *dev)
 		aup->tx_dma_ring[i]->buff_stat &= ~0xf;
 	}
 
-	aup->mac_enabled = 0;
-
 }
 
 static void au1000_reset_mac(struct net_device *dev)
@@ -1287,6 +1288,8 @@ static int au1000_probe(struct platform_device *pdev)
 	return 0;
 
 err_out:
+	if (dev->phydev)
+		phy_disconnect(dev->phydev);
 	if (aup->mii_bus)
 		mdiobus_unregister(aup->mii_bus);
 
@@ -1334,9 +1337,14 @@ static void au1000_remove(struct platform_device *pdev)
 	struct resource *base, *macen;
 
 	unregister_netdev(dev);
+	if (dev->phydev)
+		phy_disconnect(dev->phydev);
 	mdiobus_unregister(aup->mii_bus);
 	mdiobus_free(aup->mii_bus);
 
+	/* PHY teardown may have re-enabled the MAC for MDIO accesses. */
+	au1000_reset_mac(dev);
+
 	for (i = 0; i < NUM_RX_DMA; i++)
 		if (aup->rx_db_inuse[i])
 			au1000_ReleaseDB(aup, aup->rx_db_inuse[i]);
-- 
2.53.0