net: mdio: mdio-bcm-unimac: Correct rate fallback logic

[ Upstream commit a81649a4efd382497bf3d34a623360263adc6993 ]

When the parent clock is a gated clock which has multiple parents, the
clock provider (clk-scmi typically) might return a rate of 0 since there
is not one of those particular parent clocks that should be chosen for
returning a rate. Prior to ee975351cf0c ("net: mdio: mdio-bcm-unimac:
Manage clock around I/O accesses"), we would not always be passing a
clock reference depending upon how mdio-bcm-unimac was instantiated. In
that case, we would take the fallback path where the rate is hard coded
to 250MHz.

Make sure that we still fallback to using a fixed rate for the divider
calculation, otherwise we simply ignore the desired MDIO bus clock
frequency which can prevent us from interfacing with Ethernet PHYs
properly.

Fixes: ee975351cf0c ("net: mdio: mdio-bcm-unimac: Manage clock around I/O accesses")
Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250730202533.3463529-1-florian.fainelli@broadcom.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/net/mdio/mdio-bcm-unimac.c b/drivers/net/mdio/mdio-bcm-unimac.c
index b7bc70586ee0a418dadb2c318a9d1294df21e0bf..369540b43ada459c563e0e87ee8760ec742c04b8 100644 (file)
--- a/drivers/net/mdio/mdio-bcm-unimac.c
+++ b/drivers/net/mdio/mdio-bcm-unimac.c
@@ -209,10 +209,9 @@ static int unimac_mdio_clk_set(struct unimac_mdio_priv *priv)
        if (ret)
                return ret;
 
-       if (!priv->clk)
+       rate = clk_get_rate(priv->clk);
+       if (!rate)
                rate = 250000000;
-       else
-               rate = clk_get_rate(priv->clk);
 
        div = (rate / (2 * priv->clk_freq)) - 1;
        if (div & ~MDIO_CLK_DIV_MASK) {