netdev - [PATCH v2 net 1/4] net: dsa: mv88e6xxx: Improve I/O related error logging

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Message-ID: <20241219123106.730032-2-tobias@waldekranz.com>
Date: Thu, 19 Dec 2024 13:30:40 +0100
From: Tobias Waldekranz <tobias@...dekranz.com>
To: davem@...emloft.net,
	kuba@...nel.org
Cc: andrew@...n.ch,
	f.fainelli@...il.com,
	olteanv@...il.com,
	netdev@...r.kernel.org,
	linux@...linux.org.uk,
	chris.packham@...iedtelesis.co.nz,
	pabeni@...hat.com
Subject: [PATCH v2 net 1/4] net: dsa: mv88e6xxx: Improve I/O related error logging

In the rare event of an I/O error - e.g. a broken bus controller,
frozen chip, etc. - make sure to log all available information, so
that there is some hope of determining _where_ the error; not just
_that_ an error occurred.

Signed-off-by: Tobias Waldekranz <tobias@...dekranz.com>
---
 drivers/net/dsa/mv88e6xxx/chip.c | 51 +++++++++++++++++++++++++++-----
 1 file changed, 43 insertions(+), 8 deletions(-)

diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c
index 3a792f79270d..46926b769460 100644
--- a/drivers/net/dsa/mv88e6xxx/chip.c
+++ b/drivers/net/dsa/mv88e6xxx/chip.c
@@ -59,8 +59,11 @@ int mv88e6xxx_read(struct mv88e6xxx_chip *chip, int addr, int reg, u16 *val)
 	assert_reg_lock(chip);
 
 	err = mv88e6xxx_smi_read(chip, addr, reg, val);
-	if (err)
+	if (err) {
+		dev_err_ratelimited(chip->dev, "Failed to read from 0x%02x/0x%02x: %d",
+				    addr, reg, err);
 		return err;
+	}
 
 	dev_dbg(chip->dev, "<- addr: 0x%.2x reg: 0x%.2x val: 0x%.4x\n",
 		addr, reg, *val);
@@ -75,17 +78,19 @@ int mv88e6xxx_write(struct mv88e6xxx_chip *chip, int addr, int reg, u16 val)
 	assert_reg_lock(chip);
 
 	err = mv88e6xxx_smi_write(chip, addr, reg, val);
-	if (err)
+	if (err) {
+		dev_err_ratelimited(chip->dev, "Failed to write 0x%04x to 0x%02x/0x%02x: %d",
+				    val, addr, reg, err);
 		return err;
-
+	}
 	dev_dbg(chip->dev, "-> addr: 0x%.2x reg: 0x%.2x val: 0x%.4x\n",
 		addr, reg, val);
 
 	return 0;
 }
 
-int mv88e6xxx_wait_mask(struct mv88e6xxx_chip *chip, int addr, int reg,
-			u16 mask, u16 val)
+static int _mv88e6xxx_wait_mask(struct mv88e6xxx_chip *chip, int addr, int reg,
+				u16 mask, u16 val, u16 *last)
 {
 	const unsigned long timeout = jiffies + msecs_to_jiffies(50);
 	u16 data;
@@ -117,15 +122,45 @@ int mv88e6xxx_wait_mask(struct mv88e6xxx_chip *chip, int addr, int reg,
 	if ((data & mask) == val)
 		return 0;
 
-	dev_err(chip->dev, "Timeout while waiting for switch\n");
+	if (last)
+		*last = data;
+
 	return -ETIMEDOUT;
 }
 
+int mv88e6xxx_wait_mask(struct mv88e6xxx_chip *chip, int addr, int reg,
+			u16 mask, u16 val)
+{
+	u16 last;
+	int err;
+
+	err = _mv88e6xxx_wait_mask(chip, addr, reg, mask, val, &last);
+	if (!err)
+		return 0;
+
+	dev_err(chip->dev,
+		"%s waiting for 0x%02x/0x%02x to match 0x%04x (mask:0x%04x last:0x%04x)\n",
+		(err == -ETIMEDOUT) ? "Timed out" : "Failed",
+		addr, reg, val, mask, last);
+	return err;
+}
+
 int mv88e6xxx_wait_bit(struct mv88e6xxx_chip *chip, int addr, int reg,
 		       int bit, int val)
 {
-	return mv88e6xxx_wait_mask(chip, addr, reg, BIT(bit),
-				   val ? BIT(bit) : 0x0000);
+	u16 last;
+	int err;
+
+	err = _mv88e6xxx_wait_mask(chip, addr, reg, BIT(bit),
+				   val ? BIT(bit) : 0x0000, &last);
+	if (!err)
+		return 0;
+
+	dev_err(chip->dev,
+		"%s waiting for bit %d in 0x%02x/0x%02x to %s (last:0x%04x)\n",
+		(err == -ETIMEDOUT) ? "Timed out" : "Failed",
+		bit, addr, reg, val ? "set" : "clear", last);
+	return err;
 }
 
 struct mii_bus *mv88e6xxx_default_mdio_bus(struct mv88e6xxx_chip *chip)
-- 
2.43.0