netdev - [PATCH net-next v1 08/21] net: usb: lan78xx: Add error handling to set_rx_max_frame_length and set

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Message-Id: <20241203072154.2440034-9-o.rempel@pengutronix.de>
Date: Tue,  3 Dec 2024 08:21:41 +0100
From: Oleksij Rempel <o.rempel@...gutronix.de>
To: "David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Woojung Huh <woojung.huh@...rochip.com>,
	Andrew Lunn <andrew+netdev@...n.ch>
Cc: Oleksij Rempel <o.rempel@...gutronix.de>,
	kernel@...gutronix.de,
	linux-kernel@...r.kernel.org,
	netdev@...r.kernel.org,
	UNGLinuxDriver@...rochip.com,
	Phil Elwell <phil@...pberrypi.org>
Subject: [PATCH net-next v1 08/21] net: usb: lan78xx: Add error handling to set_rx_max_frame_length and set_mtu

Improve error handling in `lan78xx_set_rx_max_frame_length` by:
- Checking return values from register read/write operations and
  propagating errors.
- Exiting immediately on failure to ensure proper error reporting.

In `lan78xx_change_mtu`, log errors when changing MTU fails, using `%pe`
for clear error representation.

Signed-off-by: Oleksij Rempel <o.rempel@...gutronix.de>
---
 drivers/net/usb/lan78xx.c | 24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/drivers/net/usb/lan78xx.c b/drivers/net/usb/lan78xx.c
index 33cda7f3dd12..2d16c1fc850e 100644
--- a/drivers/net/usb/lan78xx.c
+++ b/drivers/net/usb/lan78xx.c
@@ -2599,27 +2599,36 @@ static int lan78xx_phy_init(struct lan78xx_net *dev)
 
 static int lan78xx_set_rx_max_frame_length(struct lan78xx_net *dev, int size)
 {
-	u32 buf;
 	bool rxenabled;
+	u32 buf;
+	int ret;
 
-	lan78xx_read_reg(dev, MAC_RX, &buf);
+	ret = lan78xx_read_reg(dev, MAC_RX, &buf);
+	if (ret < 0)
+		return ret;
 
 	rxenabled = ((buf & MAC_RX_RXEN_) != 0);
 
 	if (rxenabled) {
 		buf &= ~MAC_RX_RXEN_;
-		lan78xx_write_reg(dev, MAC_RX, buf);
+		ret = lan78xx_write_reg(dev, MAC_RX, buf);
+		if (ret < 0)
+			return ret;
 	}
 
 	/* add 4 to size for FCS */
 	buf &= ~MAC_RX_MAX_SIZE_MASK_;
 	buf |= (((size + 4) << MAC_RX_MAX_SIZE_SHIFT_) & MAC_RX_MAX_SIZE_MASK_);
 
-	lan78xx_write_reg(dev, MAC_RX, buf);
+	ret = lan78xx_write_reg(dev, MAC_RX, buf);
+	if (ret < 0)
+		return ret;
 
 	if (rxenabled) {
 		buf |= MAC_RX_RXEN_;
-		lan78xx_write_reg(dev, MAC_RX, buf);
+		ret = lan78xx_write_reg(dev, MAC_RX, buf);
+		if (ret < 0)
+			return ret;
 	}
 
 	return 0;
@@ -2685,7 +2694,10 @@ static int lan78xx_change_mtu(struct net_device *netdev, int new_mtu)
 		return ret;
 
 	ret = lan78xx_set_rx_max_frame_length(dev, max_frame_len);
-	if (!ret)
+	if (ret < 0)
+		netdev_err(dev->net, "MTU changed to %d from %d failed with %pe\n",
+			   new_mtu, netdev->mtu, ERR_PTR(ret));
+	else
 		WRITE_ONCE(netdev->mtu, new_mtu);
 
 	usb_autopm_put_interface(dev->intf);
-- 
2.39.5