[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 <redacted>
---
 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

Hi Trevor,

On 10/24/21 8:50 PM, Trevor Woerner wrote:

thank you for the fix!

Fixes: b7370112f519 ("lpc32xx: Added ethernet driver")
Acked-by: Vladimir Zapolskiy <vz@mleia.com>

--
Best wishes,
Vladimir

Hello:

This patch was applied to netdev/net.git (master)
by David S. Miller [off-list ref]:

On Sun, 24 Oct 2021 13:50:02 -0400 you wrote:

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 <redacted>

[...]

Here is the summary with links:
  - net: nxp: lpc_eth.c: avoid hang when bringing interface down
    https://git.kernel.org/netdev/net/c/ace19b992436

You are awesome, thank you!
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