net: phy: fix genphy_c45_eee_is_active() for disabled EEE

Commit 809265f ("net: phy: c45: remove local advertisement
parameter from genphy_c45_eee_is_active") stopped reading the local
advertisement from the PHY earlier in this development cycle, which
broke "ethtool --set-eee ethX eee off".

When ethtool is used to set EEE off, genphy_c45_eee_is_active()
indicates that EEE was active if the link partner reported an
advertisement, which causes phylib to set phydev->enable_tx_lpi on
link up, despite our local advertisement in hardware being empty.
However, phydev->advertising_eee is preserved while EEE is turned off,
which leads to genphy_c45_eee_is_active() incorrectly reporting that
EEE is active.

Fix it by checking phydev->eee_cfg.eee_enabled, and if clear,
immediately indicate that EEE is not active.

Signed-off-by: Russell King (Oracle) <[email protected]>
Reviewed-by: Andrew Lunn <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Paolo Abeni <[email protected]>

Author: Russell King (Oracle)

drivers/net/phy/phy-c45.c

@@ -1479,6 +1479,9 @@ int genphy_c45_eee_is_active(struct phy_device *phydev, unsigned long *lp)
 	__ETHTOOL_DECLARE_LINK_MODE_MASK(common);
 	int ret;
 
+	if (!phydev->eee_cfg.eee_enabled)
+		return 0;
+
 	ret = genphy_c45_read_eee_lpa(phydev, tmp_lp);
 	if (ret)
 		return ret;