netdev - [PATCH net-next 1/2] net: phy: c45 scanning: Don't consider -ENODEV fatal

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Message-Id: <20240203-unify-c22-c45-scan-error-handling-v1-1-8aa9fa3c4fca@lunn.ch>
Date: Sat, 03 Feb 2024 14:52:48 -0600
From: Andrew Lunn <andrew@...n.ch>
To: Heiner Kallweit <hkallweit1@...il.com>, 
 Russell King <linux@...linux.org.uk>, 
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
 Florian Fainelli <f.fainelli@...il.com>, 
 Vladimir Oltean <olteanv@...il.com>
Cc: netdev@...r.kernel.org, Tim Menninger <tmenninger@...estorage.com>, 
 Andrew Lunn <andrew@...n.ch>
Subject: [PATCH net-next 1/2] net: phy: c45 scanning: Don't consider
 -ENODEV fatal

When scanning the MDIO bus for C22 devices, the driver returning
-ENODEV is not considered fatal, it just indicates the MDIO bus master
knows there is no device at that address, maybe because of hardware
limitation.

Make the C45 scan code act on -ENODEV the same way, to make C22 and
C45 more uniform.

It is expected all reads for a given address will return -ENODEV, so
within get_phy_c45_ids() only the first place a read occurs has been
changed.

Signed-off-by: Andrew Lunn <andrew@...n.ch>
---
 drivers/net/phy/phy_device.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 52828d1c64f7..962ab53c23ff 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -780,7 +780,7 @@ static int get_phy_c45_devs_in_pkg(struct mii_bus *bus, int addr, int dev_addr,
  * and identifiers in @c45_ids.
  *
  * Returns zero on success, %-EIO on bus access error, or %-ENODEV if
- * the "devices in package" is invalid.
+ * the "devices in package" is invalid or no device responds.
  */
 static int get_phy_c45_ids(struct mii_bus *bus, int addr,
 			   struct phy_c45_device_ids *c45_ids)
@@ -803,7 +803,11 @@ static int get_phy_c45_ids(struct mii_bus *bus, int addr,
 			 */
 			ret = phy_c45_probe_present(bus, addr, i);
 			if (ret < 0)
-				return -EIO;
+				/* returning -ENODEV doesn't stop bus
+				 * scanning
+				 */
+				return (phy_reg == -EIO ||
+					phy_reg == -ENODEV) ? -ENODEV : -EIO;
 
 			if (!ret)
 				continue;

-- 
2.43.0