linux-kernel - [PATCH net-next v1 01/10] net: dsa: microchip: don't announce extended register support on non Gbit chips

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Message-Id: <20220729130346.2961889-2-o.rempel@pengutronix.de>
Date:   Fri, 29 Jul 2022 15:03:37 +0200
From:   Oleksij Rempel <o.rempel@...gutronix.de>
To:     Woojung Huh <woojung.huh@...rochip.com>,
        UNGLinuxDriver@...rochip.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>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>
Cc:     Oleksij Rempel <o.rempel@...gutronix.de>, kernel@...gutronix.de,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Subject: [PATCH net-next v1 01/10] net: dsa: microchip: don't announce extended register support on non Gbit chips

This issue was detected after adding support of regmap_ranges for KSZ8563R
chip. This chip is reporting extended registers support without having
actual extended registers. This made PHYlib request not existing
registers.

Signed-off-by: Oleksij Rempel <o.rempel@...gutronix.de>
---
 drivers/net/dsa/microchip/ksz9477.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/drivers/net/dsa/microchip/ksz9477.c b/drivers/net/dsa/microchip/ksz9477.c
index c108d5444695..841f0d2b15c9 100644
--- a/drivers/net/dsa/microchip/ksz9477.c
+++ b/drivers/net/dsa/microchip/ksz9477.c
@@ -264,6 +264,22 @@ void ksz9477_port_init_cnt(struct ksz_device *dev, int port)
 	mutex_unlock(&mib->cnt_mutex);
 }
 
+
+static void ksz9477_r_phy_quirks(struct ksz_device *dev, u16 addr, u16 reg,
+				 u16 *data)
+{
+	/* KSZ8563R do not have extended registers but BMSR_ESTATEN and
+	 * BMSR_ERCAP bits are set.
+	 * Since all KSZ9893 compatible chips, do not support extended
+	 * registers, it should be save to apply this quirk on complete family.
+	 * It is not possible to integrate this code in the PHY driver, since
+	 * we can't use PHYid to distinguish Gbit capable KSZ9477 PHYs from
+	 * 100Mbit KSZ8563R PHYs.
+	 */
+	if (dev->chip_id == KSZ9893_CHIP_ID && reg == MII_BMSR)
+		*data &= ~(BMSR_ESTATEN | BMSR_ERCAP);
+}
+
 void ksz9477_r_phy(struct ksz_device *dev, u16 addr, u16 reg, u16 *data)
 {
 	u16 val = 0xffff;
@@ -308,6 +324,7 @@ void ksz9477_r_phy(struct ksz_device *dev, u16 addr, u16 reg, u16 *data)
 		}
 	} else {
 		ksz_pread16(dev, addr, 0x100 + (reg << 1), &val);
+		ksz9477_r_phy_quirks(dev, addr, reg, &val);
 	}
 
 	*data = val;
-- 
2.30.2