[PATCH net-next v2 2/3] net: phylink: validate sfp_select_interface() returned interface

["Russell King (Oracle)" <rmk+kernel@armlinux.org.uk>]

Validate that the returned interface from sfp_select_interface() is
supportable by the MAC/PCS. If it isn't, print an error and return
the NA interface type. This is a preparatory step to reorganising
how a PHY on a SFP module is handled.

Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Tested-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
---
 drivers/net/phy/phylink.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
index 62d347d1112c..4049d85cb477 100644
--- a/drivers/net/phy/phylink.c
+++ b/drivers/net/phy/phylink.c
@@ -2421,11 +2421,22 @@ static phy_interface_t phylink_sfp_select_interface(struct phylink *pl,
 	phy_interface_t interface;
 
 	interface = sfp_select_interface(pl->sfp_bus, link_modes);
-	if (interface == PHY_INTERFACE_MODE_NA)
+	if (interface == PHY_INTERFACE_MODE_NA) {
 		phylink_err(pl,
 			    "selection of interface failed, advertisement %*pb\n",
 			    __ETHTOOL_LINK_MODE_MASK_NBITS,
 			    link_modes);
+		return interface;
+	}
+
+	if (!test_bit(interface, pl->config->supported_interfaces)) {
+		phylink_err(pl,
+			    "selection of interface failed, SFP selected %s (%u) but MAC supports %*pbl\n",
+			    phy_modes(interface), interface,
+			    (int)PHY_INTERFACE_MODE_MAX,
+			    pl->config->supported_interfaces);
+		return PHY_INTERFACE_MODE_NA;
+	}
 
 	return interface;
 }
-- 
2.30.2