[PATCH RFC net-next 04/13] net: phylink: ensure link is down when changing interface

[Russell King]

The only PHYs that are used with phylink which change their interface
are the BCM84881 and MV88X3310 family, both of which only change their
interface modes on link-up events.  However, rather than relying upon
this behaviour by the PHY, we should give a stronger guarantee when
resolving that the link will be down whenever we change the interface
mode.  This patch implements that stronger guarantee for resolve.

Signed-off-by: Russell King <rmk+ker...@armlinux.org.uk>
---
 drivers/net/phy/phylink.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
index 8ffe5df5c296..1507ea8a9385 100644
--- a/drivers/net/phy/phylink.c
+++ b/drivers/net/phy/phylink.c
@@ -620,8 +620,18 @@ static void phylink_resolve(struct work_struct *w)
                }
        }
 
-       if (mac_config)
+       if (mac_config) {
+               if (link_state.interface != pl->link_config.interface) {
+                       /* The interface has changed, force the link down and
+                        * then reconfigure.
+                        */
+                       if (cur_link_state) {
+                               phylink_link_down(pl);
+                               cur_link_state = false;
+                       }
+               }
                phylink_mac_config(pl, &link_state);
+       }
 
        if (link_state.link != cur_link_state) {
                pl->old_link_state = link_state.link;
-- 
2.20.1