linux-kernel - [PATCH net-next 1/3] net: phy: micrel: Fix concurrent register access

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Message-ID: <20220304093418.31645-2-Divya.Koppera@microchip.com>
Date:   Fri, 4 Mar 2022 15:04:16 +0530
From:   Divya Koppera <Divya.Koppera@...rochip.com>
To:     <netdev@...r.kernel.org>, <andrew@...n.ch>, <hkallweit1@...il.com>,
        <linux@...linux.org.uk>, <davem@...emloft.net>, <kuba@...nel.org>,
        <robh+dt@...nel.org>, <devicetree@...r.kernel.org>,
        <richardcochran@...il.com>
CC:     <linux-kernel@...r.kernel.org>, <UNGLinuxDriver@...rochip.com>,
        <madhuri.sripada@...rochip.com>, <manohar.puri@...rochip.com>
Subject: [PATCH net-next 1/3] net: phy: micrel: Fix concurrent register access

Make Extended page register accessing atomic,
to overcome unexpected output from register
reads/writes.

Fixes: 7c2dcfa295b1 ("net: phy: micrel: Add support for LAN8804 PHY")
Signed-off-by: Divya Koppera<Divya.Koppera@...rochip.com>
---
 drivers/net/phy/micrel.c | 30 ++++++++++++++++--------------
 1 file changed, 16 insertions(+), 14 deletions(-)

diff --git a/drivers/net/phy/micrel.c b/drivers/net/phy/micrel.c
index a7ebcdab415b..281cebc3d00c 100644
--- a/drivers/net/phy/micrel.c
+++ b/drivers/net/phy/micrel.c
@@ -1596,11 +1596,13 @@ static int lanphy_read_page_reg(struct phy_device *phydev, int page, u32 addr)
 {
 	u32 data;
 
-	phy_write(phydev, LAN_EXT_PAGE_ACCESS_CONTROL, page);
-	phy_write(phydev, LAN_EXT_PAGE_ACCESS_ADDRESS_DATA, addr);
-	phy_write(phydev, LAN_EXT_PAGE_ACCESS_CONTROL,
-		  (page | LAN_EXT_PAGE_ACCESS_CTRL_EP_FUNC));
-	data = phy_read(phydev, LAN_EXT_PAGE_ACCESS_ADDRESS_DATA);
+	phy_lock_mdio_bus(phydev);
+	__phy_write(phydev, LAN_EXT_PAGE_ACCESS_CONTROL, page);
+	__phy_write(phydev, LAN_EXT_PAGE_ACCESS_ADDRESS_DATA, addr);
+	__phy_write(phydev, LAN_EXT_PAGE_ACCESS_CONTROL,
+		    (page | LAN_EXT_PAGE_ACCESS_CTRL_EP_FUNC));
+	data = __phy_read(phydev, LAN_EXT_PAGE_ACCESS_ADDRESS_DATA);
+	phy_unlock_mdio_bus(phydev);
 
 	return data;
 }
@@ -1608,18 +1610,18 @@ static int lanphy_read_page_reg(struct phy_device *phydev, int page, u32 addr)
 static int lanphy_write_page_reg(struct phy_device *phydev, int page, u16 addr,
 				 u16 val)
 {
-	phy_write(phydev, LAN_EXT_PAGE_ACCESS_CONTROL, page);
-	phy_write(phydev, LAN_EXT_PAGE_ACCESS_ADDRESS_DATA, addr);
-	phy_write(phydev, LAN_EXT_PAGE_ACCESS_CONTROL,
-		  (page | LAN_EXT_PAGE_ACCESS_CTRL_EP_FUNC));
+	phy_lock_mdio_bus(phydev);
+	__phy_write(phydev, LAN_EXT_PAGE_ACCESS_CONTROL, page);
+	__phy_write(phydev, LAN_EXT_PAGE_ACCESS_ADDRESS_DATA, addr);
+	__phy_write(phydev, LAN_EXT_PAGE_ACCESS_CONTROL,
+		    page | LAN_EXT_PAGE_ACCESS_CTRL_EP_FUNC);
 
-	val = phy_write(phydev, LAN_EXT_PAGE_ACCESS_ADDRESS_DATA, val);
-	if (val) {
+	val = __phy_write(phydev, LAN_EXT_PAGE_ACCESS_ADDRESS_DATA, val);
+	if (val != 0)
 		phydev_err(phydev, "Error: phy_write has returned error %d\n",
 			   val);
-		return val;
-	}
-	return 0;
+	phy_unlock_mdio_bus(phydev);
+	return val;
 }
 
 static int lan8814_config_init(struct phy_device *phydev)
-- 
2.17.1