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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Divya Koppera <Divya.Koppera@microchip.com>,
        "David S. Miller" <davem@davemloft.net>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.16 0569/1017] net: phy: micrel: Fix concurrent register access
Date:   Tue,  5 Apr 2022 09:24:42 +0200
Message-Id: <20220405070411.169298291@linuxfoundation.org>
In-Reply-To: <20220405070354.155796697@linuxfoundation.org>
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From: Divya Koppera <Divya.Koppera@microchip.com>

[ Upstream commit 4488f6b6148045424459ef1d5b153c6895ee1dbb ]

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@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/phy/micrel.c | 32 +++++++++++++++++---------------
 1 file changed, 17 insertions(+), 15 deletions(-)

diff --git a/drivers/net/phy/micrel.c b/drivers/net/phy/micrel.c
index 76ef4e019ca9..15fe0fa78092 100644
--- a/drivers/net/phy/micrel.c
+++ b/drivers/net/phy/micrel.c
@@ -1575,11 +1575,13 @@ 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;
 }
@@ -1587,18 +1589,18 @@ 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));
-
-	val = phy_write(phydev, LAN_EXT_PAGE_ACCESS_ADDRESS_DATA, val);
-	if (val) {
+	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 != 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 lan8804_config_init(struct phy_device *phydev)
-- 
2.34.1