netdev - [PATCH net-next] r8169: fix rare issue with broken rx after link-down on RTL8125

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Date: Thu, 12 Oct 2023 08:51:13 +0200
From: Heiner Kallweit <hkallweit1@...il.com>
To: David Miller <davem@...emloft.net>, Paolo Abeni <pabeni@...hat.com>,
 Jakub Kicinski <kuba@...nel.org>, Eric Dumazet <edumazet@...gle.com>,
 Realtek linux nic maintainers <nic_swsd@...ltek.com>
Cc: "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
 Martin Kjær Jørgensen <me@...y.org>
Subject: [PATCH net-next] r8169: fix rare issue with broken rx after link-down
 on RTL8125

In very rare cases (I've seen two reports so far about different
RTL8125 chip versions) it seems the MAC locks up when link goes down
and requires a software reset to get revived.
Realtek doesn't publish hw errata information, therefore the root cause
is unknown. Realtek vendor drivers do a full hw re-initialization on
each link-up event, the slimmed-down variant here was reported to fix
the issue for the reporting user.
It's not fully clear which parts of the NIC are reset as part of the
software reset, therefore I can't rule out side effects.
Therefore apply the fix to net-next only. If no side effects are
reported, it can be submitted for stable later.

Fixes: f1bce4ad2f1c ("r8169: add support for RTL8125")
Reported-by: Martin Kjær Jørgensen <me@...y.org>
Link: https://lore.kernel.org/netdev/97ec2232-3257-316c-c3e7-a08192ce16a6@gmail.com/T/
Signed-off-by: Heiner Kallweit <hkallweit1@...il.com>
---
 drivers/net/ethernet/realtek/r8169_main.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c
index 6351a2dc1..df0df4d09 100644
--- a/drivers/net/ethernet/realtek/r8169_main.c
+++ b/drivers/net/ethernet/realtek/r8169_main.c
@@ -4596,7 +4596,11 @@ static void r8169_phylink_handler(struct net_device *ndev)
 	if (netif_carrier_ok(ndev)) {
 		rtl_link_chg_patch(tp);
 		pm_request_resume(d);
+		netif_wake_queue(tp->dev);
 	} else {
+		/* In few cases rx is broken after link-down otherwise */
+		if (rtl_is_8125(tp))
+			rtl_reset_work(tp);
 		pm_runtime_idle(d);
 	}

-- 
2.42.0