netdev - [PATCH net 2/4] net: dsa: mv88e6xxx: Give chips more time to activate their PPUs

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Message-ID: <20241206130824.3784213-3-tobias@waldekranz.com>
Date: Fri,  6 Dec 2024 14:07:34 +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
Subject: [PATCH net 2/4] net: dsa: mv88e6xxx: Give chips more time to activate their PPUs

In a daisy-chain of three 6393X devices, delays of up to 750ms are
sometimes observed before completion of PPU initialization (Global 1,
register 0, bit 15) is signaled. Therefore, allow chips more time
before giving up.

Signed-off-by: Tobias Waldekranz <tobias@...dekranz.com>
---
 drivers/net/dsa/mv88e6xxx/chip.c    |  4 ++--
 drivers/net/dsa/mv88e6xxx/chip.h    |  2 ++
 drivers/net/dsa/mv88e6xxx/global1.c | 19 ++++++++++++++++++-
 3 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c
index 16fc9a21dc59..20cd25fb4b75 100644
--- a/drivers/net/dsa/mv88e6xxx/chip.c
+++ b/drivers/net/dsa/mv88e6xxx/chip.c
@@ -145,8 +145,8 @@ int mv88e6xxx_wait_mask(struct mv88e6xxx_chip *chip, int addr, int reg,
 	return err;
 }
 
-static int _mv88e6xxx_wait_bit(struct mv88e6xxx_chip *chip, int addr, int reg,
-			       int bit, int val, u16 *last)
+int _mv88e6xxx_wait_bit(struct mv88e6xxx_chip *chip, int addr, int reg,
+			int bit, int val, u16 *last)
 {
 	return _mv88e6xxx_wait_mask(chip, addr, reg, BIT(bit),
 				   val ? BIT(bit) : 0x0000, last);
diff --git a/drivers/net/dsa/mv88e6xxx/chip.h b/drivers/net/dsa/mv88e6xxx/chip.h
index 9fe8e8a7856b..dfdb0380e664 100644
--- a/drivers/net/dsa/mv88e6xxx/chip.h
+++ b/drivers/net/dsa/mv88e6xxx/chip.h
@@ -824,6 +824,8 @@ int mv88e6xxx_read(struct mv88e6xxx_chip *chip, int addr, int reg, u16 *val);
 int mv88e6xxx_write(struct mv88e6xxx_chip *chip, int addr, int reg, u16 val);
 int mv88e6xxx_wait_mask(struct mv88e6xxx_chip *chip, int addr, int reg,
 			u16 mask, u16 val);
+int _mv88e6xxx_wait_bit(struct mv88e6xxx_chip *chip, int addr, int reg,
+			int bit, int val, u16 *last);
 int mv88e6xxx_wait_bit(struct mv88e6xxx_chip *chip, int addr, int reg,
 		       int bit, int val);
 struct mii_bus *mv88e6xxx_default_mdio_bus(struct mv88e6xxx_chip *chip);
diff --git a/drivers/net/dsa/mv88e6xxx/global1.c b/drivers/net/dsa/mv88e6xxx/global1.c
index 9820cd596757..27e98e729563 100644
--- a/drivers/net/dsa/mv88e6xxx/global1.c
+++ b/drivers/net/dsa/mv88e6xxx/global1.c
@@ -60,8 +60,25 @@ static int mv88e6185_g1_wait_ppu_polling(struct mv88e6xxx_chip *chip)
 static int mv88e6352_g1_wait_ppu_polling(struct mv88e6xxx_chip *chip)
 {
 	int bit = __bf_shf(MV88E6352_G1_STS_PPU_STATE);
+	int err, i;
 
-	return mv88e6xxx_g1_wait_bit(chip, MV88E6XXX_G1_STS, bit, 1);
+	for (i = 0; i < 20; i++) {
+		err = _mv88e6xxx_wait_bit(chip, chip->info->global1_addr,
+					  MV88E6XXX_G1_STS, bit, 1, NULL);
+		if (err != -ETIMEDOUT)
+			break;
+	}
+
+	if (err) {
+		dev_err(chip->dev, "PPU did not come online: %d\n", err);
+		return err;
+	}
+
+	if (i)
+		dev_warn(chip->dev,
+			 "PPU was slow to come online, retried %d times\n", i);
+
+	return 0;
 }
 
 static int mv88e6xxx_g1_wait_init_ready(struct mv88e6xxx_chip *chip)
-- 
2.43.0