net: pcs: xpcs: Explicitly return error on caps validation

If an unsupported interface is passed to the PCS validation callback there
is no need in further link-modes calculations since the resultant array
will be initialized with zeros which will be perceived by the phylink
subsystem as error anyway (see phylink_validate_mac_and_pcs()). Instead
let's explicitly return the -EINVAL error to inform the caller about the
unsupported interface as it's done in the rest of the pcs_validate
callbacks.

Signed-off-by: Serge Semin <fancer.lancer@gmail.com>
Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/pcs/pcs-xpcs.c

@@ -613,14 +613,15 @@ static int xpcs_validate(struct phylink_pcs *pcs, unsigned long *supported,
 
 	xpcs = phylink_pcs_to_xpcs(pcs);
 	compat = xpcs_find_compat(xpcs->id, state->interface);
+	if (!compat)
+		return -EINVAL;
 
 	/* Populate the supported link modes for this PHY interface type.
 	 * FIXME: what about the port modes and autoneg bit? This masks
 	 * all those away.
 	 */
-	if (compat)
-		for (i = 0; compat->supported[i] != __ETHTOOL_LINK_MODE_MASK_NBITS; i++)
-			set_bit(compat->supported[i], xpcs_supported);
+	for (i = 0; compat->supported[i] != __ETHTOOL_LINK_MODE_MASK_NBITS; i++)
+		set_bit(compat->supported[i], xpcs_supported);
 
 	linkmode_and(supported, supported, xpcs_supported);