linux-kernel - [net] net: usb: smsc95xx: fix external PHY reset

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Message-ID: <20221114131643.19450-1-alexandru.tachici@analog.com>
Date:   Mon, 14 Nov 2022 15:16:43 +0200
From:   Alexandru Tachici <alexandru.tachici@...log.com>
To:     <linux-kernel@...r.kernel.org>
CC:     <andrew@...n.ch>, <linux@...linux.org.uk>, <davem@...emloft.net>,
        <edumazet@...gle.com>, <kuba@...nel.org>, <pabeni@...hat.com>,
        <netdev@...r.kernel.org>, <steve.glendinning@...well.net>,
        <UNGLinuxDriver@...rochip.com>, <andre.edich@...rochip.com>,
        <linux-usb@...r.kernel.org>
Subject: [net] net: usb: smsc95xx: fix external PHY reset

An external PHY needs settling time after power up or reser.
In the bind() function an mdio bus is registered. If at this point
the external PHY is still initialising, no valid PHY ID will be
read and on phy_find_first() the bind() function will fail.

If an external PHY is present, wait the maximum time specified
in 802.3 45.2.7.1.1.

Fixes: 05b35e7eb9a1 ("smsc95xx: add phylib support")
Signed-off-by: Alexandru Tachici <alexandru.tachici@...log.com>
---
 drivers/net/usb/smsc95xx.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/net/usb/smsc95xx.c b/drivers/net/usb/smsc95xx.c
index bfb58c91db04..5ed001c0cd56 100644
--- a/drivers/net/usb/smsc95xx.c
+++ b/drivers/net/usb/smsc95xx.c
@@ -1134,8 +1134,15 @@ static int smsc95xx_bind(struct usbnet *dev, struct usb_interface *intf)
 		goto free_mdio;
 
 	is_internal_phy = !(val & HW_CFG_PSEL_);
-	if (is_internal_phy)
+	if (is_internal_phy) {
 		pdata->mdiobus->phy_mask = ~(1u << SMSC95XX_INTERNAL_PHY_ID);
+	} else {
+		/* Driver has no knowledge at this point about the external PHY.
+		 * The 802.3 specifies that the reset process shall
+		 * be completed within 0.5 s.
+		 */
+		fsleep(500000);
+	}
 
 	pdata->mdiobus->priv = dev;
 	pdata->mdiobus->read = smsc95xx_mdiobus_read;
-- 
2.34.1