From 5a8d7f126c97d04d893f5e5be2b286437a0d01b0 Mon Sep 17 00:00:00 2001 From: Florian Fainelli Date: Fri, 19 Jun 2020 11:47:46 -0700 Subject: [PATCH 1/2] of: of_mdio: Correct loop scanning logic Commit 209c65b61d94 ("drivers/of/of_mdio.c:fix of_mdiobus_register()") introduced a break of the loop on the premise that a successful registration should exit the loop. The premise is correct but not to code, because rc && rc != -ENODEV is just a special error condition, that means we would exit the loop even with rc == -ENODEV which is absolutely not correct since this is the error code to indicate to the MDIO bus layer that scanning should continue. Fix this by explicitly checking for rc = 0 as the only valid condition to break out of the loop. Fixes: 209c65b61d94 ("drivers/of/of_mdio.c:fix of_mdiobus_register()") Reviewed-by: Andrew Lunn Signed-off-by: Florian Fainelli Signed-off-by: David S. Miller --- drivers/of/of_mdio.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/drivers/of/of_mdio.c b/drivers/of/of_mdio.c index a04afe79529c..ef6f818ce5b3 100644 --- a/drivers/of/of_mdio.c +++ b/drivers/of/of_mdio.c @@ -314,10 +314,15 @@ int of_mdiobus_register(struct mii_bus *mdio, struct device_node *np) child, addr); if (of_mdiobus_child_is_phy(child)) { + /* -ENODEV is the return code that PHYLIB has + * standardized on to indicate that bus + * scanning should continue. + */ rc = of_mdiobus_register_phy(mdio, child, addr); - if (rc && rc != -ENODEV) + if (!rc) + break; + if (rc != -ENODEV) goto unregister; - break; } } } From b2ffc75e2e990b09903f9d15ccd53bc5f3a4217c Mon Sep 17 00:00:00 2001 From: Florian Fainelli Date: Fri, 19 Jun 2020 11:47:47 -0700 Subject: [PATCH 2/2] net: phy: Check harder for errors in get_phy_id() Commit 02a6efcab675 ("net: phy: allow scanning busses with missing phys") added a special condition to return -ENODEV in case -ENODEV or -EIO was returned from the first read of the MII_PHYSID1 register. In case the MDIO bus data line pull-up is not strong enough, the MDIO bus controller will not flag this as a read error. This can happen when a pluggable daughter card is not connected and weak internal pull-ups are used (since that is the only option, otherwise the pins are floating). The second read of MII_PHYSID2 will be correctly flagged an error though, but now we will return -EIO which will be treated as a hard error, thus preventing MDIO bus scanning loops to continue succesfully. Apply the same logic to both register reads, thus allowing the scanning logic to proceed. Fixes: 02a6efcab675 ("net: phy: allow scanning busses with missing phys") Reviewed-by: Andrew Lunn Signed-off-by: Florian Fainelli Signed-off-by: David S. Miller --- drivers/net/phy/phy_device.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c index 04946de74fa0..85ba95b598b5 100644 --- a/drivers/net/phy/phy_device.c +++ b/drivers/net/phy/phy_device.c @@ -794,8 +794,10 @@ static int get_phy_id(struct mii_bus *bus, int addr, u32 *phy_id, /* Grab the bits from PHYIR2, and put them in the lower half */ phy_reg = mdiobus_read(bus, addr, MII_PHYSID2); - if (phy_reg < 0) - return -EIO; + if (phy_reg < 0) { + /* returning -ENODEV doesn't stop bus scanning */ + return (phy_reg == -EIO || phy_reg == -ENODEV) ? -ENODEV : -EIO; + } *phy_id |= phy_reg;