linux-kernel - [PATCH] net: nxp: lpc_eth.c: avoid hang when bringing interface down

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Date:   Sun, 24 Oct 2021 13:50:02 -0400
From:   Trevor Woerner <twoerner@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     Vladimir Zapolskiy <vz@...ia.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        linux-arm-kernel@...ts.infradead.org (moderated list:ARM/LPC32XX SOC
        SUPPORT), netdev@...r.kernel.org (open list:NETWORKING DRIVERS)
Subject: [PATCH] net: nxp: lpc_eth.c: avoid hang when bringing interface down

A hard hang is observed whenever the ethernet interface is brought
down. If the PHY is stopped before the LPC core block is reset,
the SoC will hang. Comparing lpc_eth_close() and lpc_eth_open() I
re-arranged the ordering of the functions calls in lpc_eth_close() to
reset the hardware before stopping the PHY.

Signed-off-by: Trevor Woerner <twoerner@...il.com>
---
 drivers/net/ethernet/nxp/lpc_eth.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/nxp/lpc_eth.c b/drivers/net/ethernet/nxp/lpc_eth.c
index d29fe562b3de..c910fa2f40a4 100644
--- a/drivers/net/ethernet/nxp/lpc_eth.c
+++ b/drivers/net/ethernet/nxp/lpc_eth.c
@@ -1015,9 +1015,6 @@ static int lpc_eth_close(struct net_device *ndev)
 	napi_disable(&pldat->napi);
 	netif_stop_queue(ndev);
 
-	if (ndev->phydev)
-		phy_stop(ndev->phydev);
-
 	spin_lock_irqsave(&pldat->lock, flags);
 	__lpc_eth_reset(pldat);
 	netif_carrier_off(ndev);
@@ -1025,6 +1022,8 @@ static int lpc_eth_close(struct net_device *ndev)
 	writel(0, LPC_ENET_MAC2(pldat->net_base));
 	spin_unlock_irqrestore(&pldat->lock, flags);
 
+	if (ndev->phydev)
+		phy_stop(ndev->phydev);
 	clk_disable_unprepare(pldat->clk);
 
 	return 0;
-- 
2.30.0.rc0