netdev - [PATCH net-next 1/2] net: pcs: xpcs: remove double-read of link state when using AN

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Date:   Wed, 15 Mar 2023 14:46:43 +0000
From:   "Russell King (Oracle)" <rmk+kernel@...linux.org.uk>
To:     Andrew Lunn <andrew@...n.ch>,
        Ioana Ciornei <ioana.ciornei@....com>,
        Jonathan McDowell <noodles@...th.li>,
        Jose Abreu <Jose.Abreu@...opsys.com>,
        Vladimir Oltean <olteanv@...il.com>
Cc:     Heiner Kallweit <hkallweit1@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org
Subject: [PATCH net-next 1/2] net: pcs: xpcs: remove double-read of link state
 when using AN

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 dbae3388ea9c ("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: fcb26bd2b6ca ("net: phy: Add Synopsys DesignWare XPCS MDIO module")
Signed-off-by: Russell King (Oracle) <rmk+kernel@...linux.org.uk>
---
 drivers/net/pcs/pcs-xpcs.c | 13 ++-----------
 1 file changed, 2 insertions(+), 11 deletions(-)

diff --git a/drivers/net/pcs/pcs-xpcs.c b/drivers/net/pcs/pcs-xpcs.c
index bc428a816719..04a685353041 100644
--- a/drivers/net/pcs/pcs-xpcs.c
+++ b/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);
-- 
2.30.2