netdev - [[PATCH,net]] net: dsa: mt7530: Change the LINK bit to reflect the link status

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Date:   Thu, 19 Mar 2020 14:47:56 +0100
From:   René van Dorst <opensource@...rst.com>
To:     netdev@...r.kernel.org
Cc:     Frank Wunderlich <frank-w@...lic-files.de>,
        DENG Qingfang <dqfext@...il.com>,
        Landen Chao <landen.chao@...iatek.com>,
        Sean Wang <sean.wang@...iatek.com>,
        Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Russell King <linux@...linux.org.uk>,
        linux-mediatek@...ts.infradead.org,
        René van Dorst <opensource@...rst.com>,
        Andrew Smith <andrew.smith@...i.com>
Subject: [[PATCH,net]] net: dsa: mt7530: Change the LINK bit to reflect the link status

Andrew reported:

After a number of network port link up/down changes, sometimes the switch
port gets stuck in a state where it thinks it is still transmitting packets
but the cpu port is not actually transmitting anymore. In this state you
will see a message on the console
"mtk_soc_eth 1e100000.ethernet eth0: transmit timed out" and the Tx counter
in ifconfig will be incrementing on virtual port, but not incrementing on
cpu port.

The issue is that MAC TX/RX status has no impact on the link status or
queue manager of the switch. So the queue manager just queues up packets
of a disabled port and sends out pause frames when the queue is full.

Change the LINK bit to reflect the link status.

Fixes: b8f126a8d543 ("net-next: dsa: add dsa support for Mediatek MT7530 switch")
Reported-by: Andrew Smith <andrew.smith@...i.com>
Signed-off-by: René van Dorst <opensource@...rst.com>
---
 drivers/net/dsa/mt7530.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/dsa/mt7530.c b/drivers/net/dsa/mt7530.c
index 9ee3f263d529..d422d3d6a129 100644
--- a/drivers/net/dsa/mt7530.c
+++ b/drivers/net/dsa/mt7530.c
@@ -566,7 +566,7 @@ mt7530_mib_reset(struct dsa_switch *ds)
 static void
 mt7530_port_set_status(struct mt7530_priv *priv, int port, int enable)
 {
-	u32 mask = PMCR_TX_EN | PMCR_RX_EN;
+	u32 mask = PMCR_TX_EN | PMCR_RX_EN | PMCR_FORCE_LNK;
 
 	if (enable)
 		mt7530_set(priv, MT7530_PMCR_P(port), mask);
@@ -1512,7 +1512,7 @@ static void mt7530_phylink_mac_config(struct dsa_switch *ds, int port,
 	mcr_new &= ~(PMCR_FORCE_SPEED_1000 | PMCR_FORCE_SPEED_100 |
 		     PMCR_FORCE_FDX | PMCR_TX_FC_EN | PMCR_RX_FC_EN);
 	mcr_new |= PMCR_IFG_XMIT(1) | PMCR_MAC_MODE | PMCR_BACKOFF_EN |
-		   PMCR_BACKPR_EN | PMCR_FORCE_MODE | PMCR_FORCE_LNK;
+		   PMCR_BACKPR_EN | PMCR_FORCE_MODE;
 
 	/* Are we connected to external phy */
 	if (port == 5 && dsa_is_user_port(ds, 5))
-- 
2.25.1