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Message-Id: <20241013052916.3115142-1-o.rempel@pengutronix.de>
Date: Sun, 13 Oct 2024 07:29:16 +0200
From: Oleksij Rempel <o.rempel@...gutronix.de>
To: Nicolas Ferre <nicolas.ferre@...rochip.com>,
Claudiu Beznea <claudiu.beznea@...rochip.com>,
"David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>
Cc: Oleksij Rempel <o.rempel@...gutronix.de>,
stable@...r.kernel.org,
Andrew Lunn <andrew@...n.ch>,
kernel@...gutronix.de,
linux-kernel@...r.kernel.org,
netdev@...r.kernel.org,
Codrin Ciubotariu <codrin.ciubotariu@...rochip.com>
Subject: [PATCH net v2 1/1] net: macb: Avoid 20s boot delay by skipping MDIO bus registration for fixed-link PHY
A boot delay was introduced by commit 79540d133ed6 ("net: macb: Fix
handling of fixed-link node"). This delay was caused by the call to
`mdiobus_register()` in cases where a fixed-link PHY was present. The
MDIO bus registration triggered unnecessary PHY address scans, leading
to a 20-second delay due to attempts to detect Clause 45 (C45)
compatible PHYs, despite no MDIO bus being attached.
The commit 79540d133ed6 ("net: macb: Fix handling of fixed-link node")
was originally introduced to fix a regression caused by commit
7897b071ac3b4 ("net: macb: convert to phylink"), which caused the driver
to misinterpret fixed-link nodes as PHY nodes. This resulted in warnings
like:
mdio_bus f0028000.ethernet-ffffffff: fixed-link has invalid PHY address
mdio_bus f0028000.ethernet-ffffffff: scan phy fixed-link at address 0
...
mdio_bus f0028000.ethernet-ffffffff: scan phy fixed-link at address 31
This patch reworks the logic to avoid registering and allocation of the
MDIO bus when:
- The device tree contains a fixed-link node.
- There is no "mdio" child node in the device tree.
If a child node named "mdio" exists, the MDIO bus will be registered to
support PHYs attached to the MACB's MDIO bus. Otherwise, with only a
fixed-link, the MDIO bus is skipped.
Tested on a sama5d35 based system with a ksz8863 switch attached to
macb0.
Fixes: 79540d133ed6 ("net: macb: Fix handling of fixed-link node")
Signed-off-by: Oleksij Rempel <o.rempel@...gutronix.de>
Cc: stable@...r.kernel.org
Reviewed-by: Andrew Lunn <andrew@...n.ch>
---
changes v2:
- s/some PHYs may be attached/some devices may be attached/
---
drivers/net/ethernet/cadence/macb_main.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)
diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index f06babec04a0b..56901280ba047 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -930,9 +930,6 @@ static int macb_mdiobus_register(struct macb *bp)
return ret;
}
- if (of_phy_is_fixed_link(np))
- return mdiobus_register(bp->mii_bus);
-
/* Only create the PHY from the device tree if at least one PHY is
* described. Otherwise scan the entire MDIO bus. We do this to support
* old device tree that did not follow the best practices and did not
@@ -953,8 +950,19 @@ static int macb_mdiobus_register(struct macb *bp)
static int macb_mii_init(struct macb *bp)
{
+ struct device_node *child, *np = bp->pdev->dev.of_node;
int err = -ENXIO;
+ /* With fixed-link, we don't need to register the MDIO bus,
+ * except if we have a child named "mdio" in the device tree.
+ * In that case, some devices may be attached to the MACB's MDIO bus.
+ */
+ child = of_get_child_by_name(np, "mdio");
+ if (child)
+ of_node_put(child);
+ else if (of_phy_is_fixed_link(np))
+ return macb_mii_probe(bp->dev);
+
/* Enable management port */
macb_writel(bp, NCR, MACB_BIT(MPE));
--
2.39.5
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