netdev - [PATCH v2 net] net: stmmac: dwmac4: extend timeout for VLAN Tag register busy bit check

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Message-Id: <20240918193452.417115-1-shenwei.wang@nxp.com>
Date: Wed, 18 Sep 2024 14:34:52 -0500
From: Shenwei Wang <shenwei.wang@....com>
To: "David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Maxime Coquelin <mcoquelin.stm32@...il.com>,
	horms@...nel.org
Cc: Alexandre Torgue <alexandre.torgue@...s.st.com>,
	Jose Abreu <joabreu@...opsys.com>,
	Ong Boon Leong <boon.leong.ong@...el.com>,
	Wong Vee Khee <vee.khee.wong@...el.com>,
	Chuah Kim Tatt <kim.tatt.chuah@...el.com>,
	netdev@...r.kernel.org,
	linux-stm32@...md-mailman.stormreply.com,
	linux-arm-kernel@...ts.infradead.org,
	imx@...ts.linux.dev,
	linux-imx@....com,
	Shenwei Wang <shenwei.wang@....com>
Subject: [PATCH v2 net] net: stmmac: dwmac4: extend timeout for VLAN Tag register busy bit check

Increase the timeout for checking the busy bit of the VLAN Tag register
from 10µs to 500ms. This change is necessary to accommodate scenarios
where Energy Efficient Ethernet (EEE) is enabled.

Overnight testing revealed that when EEE is active, the busy bit can
remain set for up to approximately 300ms. The new 500ms timeout provides
a safety margin.

Fixes: ed64639bc1e0 ("net: stmmac: Add support for VLAN Rx filtering")
Signed-off-by: Shenwei Wang <shenwei.wang@....com>
---
Changes in v2:
 - replace the udelay with readl_poll_timeout per Simon's review.

---
 drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c b/drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c
index a1858f083eef..a0cfa2eaebb4 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c
@@ -14,6 +14,7 @@
 #include <linux/slab.h>
 #include <linux/ethtool.h>
 #include <linux/io.h>
+#include <linux/iopoll.h>
 #include "stmmac.h"
 #include "stmmac_pcs.h"
 #include "dwmac4.h"
@@ -471,7 +472,7 @@ static int dwmac4_write_vlan_filter(struct net_device *dev,
 				    u8 index, u32 data)
 {
 	void __iomem *ioaddr = (void __iomem *)dev->base_addr;
-	int i, timeout = 10;
+	int ret, timeout = 500000; //500ms
 	u32 val;

 	if (index >= hw->num_vlan)
@@ -487,12 +488,11 @@ static int dwmac4_write_vlan_filter(struct net_device *dev,

 	writel(val, ioaddr + GMAC_VLAN_TAG);

-	for (i = 0; i < timeout; i++) {
-		val = readl(ioaddr + GMAC_VLAN_TAG);
-		if (!(val & GMAC_VLAN_TAG_CTRL_OB))
-			return 0;
-		udelay(1);
-	}
+	ret = readl_poll_timeout(ioaddr + GMAC_VLAN_TAG, val,
+				 !(val & GMAC_VLAN_TAG_CTRL_OB),
+				 1000, timeout);
+	if (!ret)
+		return 0;

 	netdev_err(dev, "Timeout accessing MAC_VLAN_Tag_Filter\n");

--
2.34.1