[PATCH net-next] net: phylink: allow PHYs to be attached in 802.3z inband mode

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

Now that we have proper decision making for inband mode support which
makes it a "best efforts" feature based on the capabilities of the PHY
and PCS, we can relax whether we expect and permit a PHY to be
attached. This is especially true for the 2500BASE-X case which some
PHYs use without inband on their host side interface for 2.5G speeds,
but use inband for slower speeds switching to SGMII on their host side
interface.

We already have such a case for some qcom-ethqos setups, although
qcom-ethqos overrides phylink's inband settings by accessing the PCS
directly at the moment. This should allow qcom-ethqos to transition to
defaulting to inband when 2500BASE-X or SGMII is specified in its DTS.

Allow PHYs to be attached when inband mode has been specified, which
will be necessary to allow inband mode to be used on qcom-ethqos.

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
---
 drivers/net/phy/phylink.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
index 087ac63f9193..1c178038e6f1 100644
--- a/drivers/net/phy/phylink.c
+++ b/drivers/net/phy/phylink.c
@@ -1965,9 +1965,7 @@ EXPORT_SYMBOL_GPL(phylink_destroy);
  */
 bool phylink_expects_phy(struct phylink *pl)
 {
-	if (pl->cfg_link_an_mode == MLO_AN_FIXED ||
-	    (pl->cfg_link_an_mode == MLO_AN_INBAND &&
-	     phy_interface_mode_is_8023z(pl->link_interface)))
+	if (pl->cfg_link_an_mode == MLO_AN_FIXED)
 		return false;
 	return true;
 }
@@ -2206,9 +2204,7 @@ static int phylink_attach_phy(struct phylink *pl, struct phy_device *phy,
 {
 	u32 flags = 0;
 
-	if (WARN_ON(pl->cfg_link_an_mode == MLO_AN_FIXED ||
-		    (pl->cfg_link_an_mode == MLO_AN_INBAND &&
-		     phy_interface_mode_is_8023z(interface) && !pl->sfp_bus)))
+	if (WARN_ON(pl->cfg_link_an_mode == MLO_AN_FIXED))
 		return -EINVAL;
 
 	if (pl->phydev)
-- 
2.47.3