[PATCH net] net: stmmac: Select sleep pin state after suspending phylink

[Fabio Estevam <festevam@gmail.com>]

From: Clark Wang <xiaoning.wang@nxp.com>

When MAC Wake-on-LAN is disabled, stmmac_suspend() selects the sleep
pinctrl state before calling phylink_suspend().

phylink_suspend() may access PHY registers over MDIO while stopping or
reconfiguring the PHY. If selecting the sleep state muxes the MDC and
MDIO pins away from the MDIO bus function, these accesses no longer work.

Select the sleep pin state only after phylink_suspend() has completed.

Keep the transition conditional on MAC Wake-on-LAN being disabled so
that the pins remain active when the MAC must receive wake-up packets.

Fixes: 90702dcd19c0 ("net: stmmac: fix MAC not working when system resume back with WoL active")
Signed-off-by: Clark Wang <xiaoning.wang@nxp.com>
[fabio: Reworded subject/commit log for clarity and made it priv->wolopts conditional]
Signed-off-by: Fabio Estevam <festevam@gmail.com>
---
Based on the NXP kernel fix:

https://github.com/nxp-imx/linux-imx/commit/7905fa71ed07d8c2f1da88ad9fffd5ac5e89461f

 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 0de4bc949913..36ab66ad80fd 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -8183,13 +8183,15 @@ int stmmac_suspend(struct device *dev)
 		priv->irq_wake = 1;
 	} else {
 		stmmac_mac_set(priv, priv->ioaddr, false);
-		pinctrl_pm_select_sleep_state(priv->device);
 	}
 
 	mutex_unlock(&priv->lock);
 
 	rtnl_lock();
 	phylink_suspend(priv->phylink, !!priv->wolopts);
+
+	if (!priv->wolopts)
+		pinctrl_pm_select_sleep_state(priv->device);
 	rtnl_unlock();
 
 	if (stmmac_fpe_supported(priv))
-- 
2.43.0