netdev - [RFC PATCH net-next 3/3] net: mdio: ipq8064: enlarge sleep after read/write operation

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Message-Id: <20210511021110.17522-3-ansuelsmth@gmail.com>
Date:   Tue, 11 May 2021 04:11:10 +0200
From:   Ansuel Smith <ansuelsmth@...il.com>
To:     Andrew Lunn <andrew@...n.ch>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Russell King <linux@...linux.org.uk>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        netdev@...r.kernel.org (open list:ETHERNET PHY LIBRARY),
        linux-kernel@...r.kernel.org (open list)
Cc:     Ansuel Smith <ansuelsmth@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>
Subject: [RFC PATCH net-next 3/3] net: mdio: ipq8064: enlarge sleep after read/write operation

With the use of the qca8k dsa driver, some problem arised related to
port status detection. With a load on a specific port (for example a
simple speed test), the driver starts to behave in a strange way and
garbage data is produced. To address this, enlarge the sleep delay and
address a bug for the reg offset 31 that require additional delay for
this specific reg.

Signed-off-by: Ansuel Smith <ansuelsmth@...il.com>
Reviewed-by: Florian Fainelli <f.fainelli@...il.com>
---
 drivers/net/mdio/mdio-ipq8064.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/net/mdio/mdio-ipq8064.c b/drivers/net/mdio/mdio-ipq8064.c
index 14b3c310af73..bd1aea2d5a26 100644
--- a/drivers/net/mdio/mdio-ipq8064.c
+++ b/drivers/net/mdio/mdio-ipq8064.c
@@ -65,7 +65,7 @@ ipq8064_mdio_read(struct mii_bus *bus, int phy_addr, int reg_offset)
 		   ((reg_offset << MII_REG_SHIFT) & MII_REG_MASK);
 
 	regmap_write(priv->base, MII_ADDR_REG_ADDR, miiaddr);
-	usleep_range(8, 10);
+	usleep_range(10, 13);
 
 	err = ipq8064_mdio_wait_busy(priv);
 	if (err)
@@ -91,7 +91,14 @@ ipq8064_mdio_write(struct mii_bus *bus, int phy_addr, int reg_offset, u16 data)
 		   ((reg_offset << MII_REG_SHIFT) & MII_REG_MASK);
 
 	regmap_write(priv->base, MII_ADDR_REG_ADDR, miiaddr);
-	usleep_range(8, 10);
+
+	/* For the specific reg 31 extra time is needed or the next
+	 * read will produce garbage data.
+	 */
+	if (reg_offset == 31)
+		usleep_range(30, 43);
+	else
+		usleep_range(10, 13);
 
 	return ipq8064_mdio_wait_busy(priv);
 }
-- 
2.30.2