netdev - [PATCH net-next v3 3/7] usbnet: smsc95xx: Don't reset PHY behind PHY driver's back

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Message-Id: <53ea51cabb288a0eba475ffaf1b2afd15b505b62.1652343655.git.lukas@wunner.de>
Date:   Thu, 12 May 2022 10:42:03 +0200
From:   Lukas Wunner <lukas@...ner.de>
To:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Eric Dumazet <edumazet@...gle.com>
Cc:     netdev@...r.kernel.org, linux-usb@...r.kernel.org,
        Steve Glendinning <steve.glendinning@...well.net>,
        UNGLinuxDriver@...rochip.com, Oliver Neukum <oneukum@...e.com>,
        Andre Edich <andre.edich@...rochip.com>,
        Oleksij Rempel <linux@...pel-privat.de>,
        Martyn Welch <martyn.welch@...labora.com>,
        Gabriel Hojda <ghojda@...urs.ro>,
        Christoph Fritz <chf.fritz@...glemail.com>,
        Lino Sanfilippo <LinoSanfilippo@....de>,
        Philipp Rosenberger <p.rosenberger@...bus.com>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Andrew Lunn <andrew@...n.ch>,
        Russell King <linux@...linux.org.uk>,
        Ferry Toth <fntoth@...il.com>
Subject: [PATCH net-next v3 3/7] usbnet: smsc95xx: Don't reset PHY behind PHY
 driver's back

smsc95xx_reset() resets the PHY behind the PHY driver's back, which
seems like a bad idea generally.  Remove that portion of the function.

We're about to use PHY interrupts instead of polling to detect link
changes on SMSC LAN95xx chips.  Because smsc95xx_reset() is called from
usbnet_open(), PHY interrupt settings are lost whenever the net_device
is brought up.

There are two other callers of smsc95xx_reset(), namely smsc95xx_bind()
and smsc95xx_reset_resume(), and both may indeed benefit from a PHY
reset.  However they already perform one through their calls to
phy_connect_direct() and phy_init_hw().

Tested-by: Oleksij Rempel <o.rempel@...gutronix.de> # LAN9514/9512/9500
Tested-by: Ferry Toth <fntoth@...il.com> # LAN9514
Signed-off-by: Lukas Wunner <lukas@...ner.de>
Cc: Martyn Welch <martyn.welch@...labora.com>
Cc: Gabriel Hojda <ghojda@...urs.ro>
---
 drivers/net/usb/smsc95xx.c | 18 ------------------
 1 file changed, 18 deletions(-)

diff --git a/drivers/net/usb/smsc95xx.c b/drivers/net/usb/smsc95xx.c
index 2cb44d65bbc3..6c37c7adde1b 100644
--- a/drivers/net/usb/smsc95xx.c
+++ b/drivers/net/usb/smsc95xx.c
@@ -887,24 +887,6 @@ static int smsc95xx_reset(struct usbnet *dev)
 		return ret;
 	}
 
-	ret = smsc95xx_write_reg(dev, PM_CTRL, PM_CTL_PHY_RST_);
-	if (ret < 0)
-		return ret;
-
-	timeout = 0;
-	do {
-		msleep(10);
-		ret = smsc95xx_read_reg(dev, PM_CTRL, &read_buf);
-		if (ret < 0)
-			return ret;
-		timeout++;
-	} while ((read_buf & PM_CTL_PHY_RST_) && (timeout < 100));
-
-	if (timeout >= 100) {
-		netdev_warn(dev->net, "timeout waiting for PHY Reset\n");
-		return ret;
-	}
-
 	ret = smsc95xx_set_mac_address(dev);
 	if (ret < 0)
 		return ret;
-- 
2.35.2