net: pcs: xpcs: remove double-read of link state when using AN

[ Upstream commit ef63461 ]

Phylink does not want the current state of the link when reading the
PCS link state - it wants the latched state. Don't double-read the
MII status register. Phylink will re-read as necessary to capture
transient link-down events as of dbae338 ("net: phylink: Force
retrigger in case of latched link-fail indicator").

The above referenced commit is a dependency for this change, and thus
this change should not be backported to any kernel that does not
contain the above referenced commit.

Fixes: fcb26bd ("net: phy: Add Synopsys DesignWare XPCS MDIO module")
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/net/pcs/pcs-xpcs.c

@@ -321,7 +321,7 @@ static int xpcs_read_fault_c73(struct dw_xpcs *xpcs,
 	return 0;
 }
 
-static int xpcs_read_link_c73(struct dw_xpcs *xpcs, bool an)
+static int xpcs_read_link_c73(struct dw_xpcs *xpcs)
 {
 	bool link = true;
 	int ret;
@@ -333,15 +333,6 @@ static int xpcs_read_link_c73(struct dw_xpcs *xpcs, bool an)
 	if (!(ret & MDIO_STAT1_LSTATUS))
 		link = false;
 
-	if (an) {
-		ret = xpcs_read(xpcs, MDIO_MMD_AN, MDIO_STAT1);
-		if (ret < 0)
-			return ret;
-
-		if (!(ret & MDIO_STAT1_LSTATUS))
-			link = false;
-	}
-
 	return link;
 }
 
@@ -935,7 +926,7 @@ static int xpcs_get_state_c73(struct dw_xpcs *xpcs,
 	int ret;
 
 	/* Link needs to be read first ... */
-	state->link = xpcs_read_link_c73(xpcs, state->an_enabled) > 0 ? 1 : 0;
+	state->link = xpcs_read_link_c73(xpcs) > 0 ? 1 : 0;
 
 	/* ... and then we check the faults. */
 	ret = xpcs_read_fault_c73(xpcs, state);