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net: phy: Check harder for errors in get_phy_id()

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Commit 02a6efcab6 ("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: 02a6efcab6 ("net: phy: allow scanning busses with missing phys")
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Florian Fainelli 2020-06-19 11:47:47 -07:00 committed by David S. Miller
parent 5a8d7f126c
commit b2ffc75e2e
1 changed files with 4 additions and 2 deletions
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6
drivers/net/phy/phy_device.c
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@ -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;