netdev - [PATCH] net: dsa: mv88e6xxx: Update mv88e6393x serdes errata

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Message-Id: <20210824064413.95675-1-nathan@nathanrossi.com>
Date:   Tue, 24 Aug 2021 06:44:13 +0000
From:   Nathan Rossi <nathan@...hanrossi.com>
To:     netdev@...r.kernel.org
Cc:     Nathan Rossi <nathan@...hanrossi.com>,
        Nathan Rossi <nathan.rossi@...i.com>,
        Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Subject: [PATCH] net: dsa: mv88e6xxx: Update mv88e6393x serdes errata

From: Nathan Rossi <nathan.rossi@...i.com>

In early erratas this issue only covered port 0 when changing from
[x]MII (rev A 3.6). In subsequent errata versions this errata changed to
cover the additional "Hardware reset in CPU managed mode" condition, and
removed the note specifying that it only applied to port 0.

In designs where the device is configured with CPU managed mode
(CPU_MGD), on reset all SERDES ports (p0, p9, p10) have a stuck power
down bit and require this initial power up procedure. As such apply this
errata to all three SERDES ports of the mv88e6393x.

Signed-off-by: Nathan Rossi <nathan.rossi@...i.com>
---
 drivers/net/dsa/mv88e6xxx/serdes.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/net/dsa/mv88e6xxx/serdes.c b/drivers/net/dsa/mv88e6xxx/serdes.c
index b1d46dd8ea..6ea0036787 100644
--- a/drivers/net/dsa/mv88e6xxx/serdes.c
+++ b/drivers/net/dsa/mv88e6xxx/serdes.c
@@ -1277,15 +1277,16 @@ static int mv88e6393x_serdes_port_errata(struct mv88e6xxx_chip *chip, int lane)
 	int err;
 
 	/* mv88e6393x family errata 4.6:
-	 * Cannot clear PwrDn bit on SERDES on port 0 if device is configured
-	 * CPU_MGD mode or P0_mode is configured for [x]MII.
-	 * Workaround: Set Port0 SERDES register 4.F002 bit 5=0 and bit 15=1.
+	 * Cannot clear PwrDn bit on SERDES if device is configured CPU_MGD
+	 * mode or P0_mode is configured for [x]MII.
+	 * Workaround: Set SERDES register 4.F002 bit 5=0 and bit 15=1.
 	 *
 	 * It seems that after this workaround the SERDES is automatically
 	 * powered up (the bit is cleared), so power it down.
 	 */
-	if (lane == MV88E6393X_PORT0_LANE) {
-		err = mv88e6390_serdes_read(chip, MV88E6393X_PORT0_LANE,
+	if (lane == MV88E6393X_PORT0_LANE || lane == MV88E6393X_PORT9_LANE ||
+	    lane == MV88E6393X_PORT10_LANE) {
+		err = mv88e6390_serdes_read(chip, lane,
 					    MDIO_MMD_PHYXS,
 					    MV88E6393X_SERDES_POC, &reg);
 		if (err)
---
2.33.0