netdev - [PATCH 2/2] net: dsa: mv88e6xxx: move call to mv88e6xxx_mdios

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Date:   Sat, 11 Mar 2023 10:41:41 +0100
From:   Klaus Kudielka <klaus.kudielka@...il.com>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     Florian Fainelli <f.fainelli@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Richard Cochran <richardcochran@...il.com>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Klaus Kudielka <klaus.kudielka@...il.com>
Subject: [PATCH 2/2] net: dsa: mv88e6xxx: move call to mv88e6xxx_mdios_register()

>From commit 1a136ca2e089 ("net: mdio: scan bus based on bus capabilities
for C22 and C45") onwards, mdiobus_scan_bus_c45() is being called on buses
with MDIOBUS_NO_CAP. On a Turris Omnia (Armada 385, 88E6176 switch), this
causes a significant increase of boot time, from 1.6 seconds, to 6.3
seconds. The boot time stated here is until start of /init.

Further testing revealed that the C45 scan is indeed expensive (around
2.7 seconds, due to a huge number of bus transactions), and called twice.

It was suggested, to call mv88e6xxx_mdios_register() at the beginning of
mv88e6xxx_setup(), and mv88e6xxx_mdios_unregister() at the end of
mv88e6xxx_teardown(). This is accomplished by this patch.

Testing on the Turris Omnia revealed, that this improves the situation.
Now mdiobus_scan_bus_c45() is called only once, ending up in a boot time
of 4.3 seconds.

Link: https://lore.kernel.org/lkml/449bde236c08d5ab5e54abd73b645d8b29955894.camel@gmail.com/
Suggested-by: Andrew Lunn <andrew@...n.ch>
Tested-by: Klaus Kudielka <klaus.kudielka@...il.com>
Signed-off-by: Klaus Kudielka <klaus.kudielka@...il.com>
---
 drivers/net/dsa/mv88e6xxx/chip.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c
index 496015baac..8c0fa4cfcd 100644
--- a/drivers/net/dsa/mv88e6xxx/chip.c
+++ b/drivers/net/dsa/mv88e6xxx/chip.c
@@ -3840,9 +3840,9 @@ static void mv88e6xxx_mdios_unregister(struct mv88e6xxx_chip *chip)
 	}
 }
 
-static int mv88e6xxx_mdios_register(struct mv88e6xxx_chip *chip,
-				    struct device_node *np)
+static int mv88e6xxx_mdios_register(struct mv88e6xxx_chip *chip)
 {
+	struct device_node *np = chip->dev->of_node;
 	struct device_node *child;
 	int err;
 
@@ -3877,9 +3877,12 @@ static int mv88e6xxx_mdios_register(struct mv88e6xxx_chip *chip,
 
 static void mv88e6xxx_teardown(struct dsa_switch *ds)
 {
+	struct mv88e6xxx_chip *chip = ds->priv;
+
 	mv88e6xxx_teardown_devlink_params(ds);
 	dsa_devlink_resources_unregister(ds);
 	mv88e6xxx_teardown_devlink_regions_global(ds);
+	mv88e6xxx_mdios_unregister(chip);
 }
 
 static int mv88e6xxx_setup(struct dsa_switch *ds)
@@ -3889,6 +3892,10 @@ static int mv88e6xxx_setup(struct dsa_switch *ds)
 	int err;
 	int i;
 
+	err = mv88e6xxx_mdios_register(chip);
+	if (err)
+		return err;
+
 	chip->ds = ds;
 	ds->slave_mii_bus = mv88e6xxx_default_mdio_bus(chip);
 
@@ -7220,18 +7227,12 @@ static int mv88e6xxx_probe(struct mdio_device *mdiodev)
 	if (err)
 		goto out_g1_atu_prob_irq;
 
-	err = mv88e6xxx_mdios_register(chip, np);
-	if (err)
-		goto out_g1_vtu_prob_irq;
-
 	err = mv88e6xxx_register_switch(chip);
 	if (err)
-		goto out_mdio;
+		goto out_g1_vtu_prob_irq;
 
 	return 0;
 
-out_mdio:
-	mv88e6xxx_mdios_unregister(chip);
 out_g1_vtu_prob_irq:
 	mv88e6xxx_g1_vtu_prob_irq_free(chip);
 out_g1_atu_prob_irq:
@@ -7268,7 +7269,6 @@ static void mv88e6xxx_remove(struct mdio_device *mdiodev)
 
 	mv88e6xxx_phy_destroy(chip);
 	mv88e6xxx_unregister_switch(chip);
-	mv88e6xxx_mdios_unregister(chip);
 
 	mv88e6xxx_g1_vtu_prob_irq_free(chip);
 	mv88e6xxx_g1_atu_prob_irq_free(chip);
-- 
2.39.2