net: phy: qca83xx: read resolved QCA8337 link status

After a QCA8337 SmartSpeed downshift, genphy_read_status() can report
1000 Mbit/s from the advertised modes when the PHY is running at
100 Mbit/s. On a Redmi AX5400 running downstream OpenWrt Linux 6.18.52,
this caused qca8k to program the user-port MAC for 1000 Mbit/s and
traffic failed. An earlier prototype that read the resolved speed
from the PHY restored traffic.

Wrap genphy_read_status() and use at803x_read_specific_status() to
replace its speed and duplex result when an autonegotiated link comes
up. Resolve pause for the resulting duplex. Until the PHY reports a
resolved speed and duplex, report the link as down so that the next
poll reads them again, as marvell_read_status_page_an() does. In that
case also clear the duplex, master/slave state and link partner modes
that genphy_read_status() read for an up link. QCA8337's register
layout matches the helper (data sheet 80-Y0619-3 Rev. D, pages
327-328).

Keep the generic master/slave read order and the early return for a
steady autonegotiated link. This avoids additional reads of the
clear-on-read idle error count in MII_STAT1000. Forced mode continues
to use BMCR. Report the MDI-X state read at link-up and invalidate it
when the link goes down or autonegotiation is disabled. Clear
mdix_ctrl because this driver does not implement MDI-X configuration.

The QCA8327 entries keep genphy_read_status(). The AR8327 data sheet
(MKG-15791 Rev. 1.0) lists the QCA8327-A PHY ID and documents the same
PHY-specific status layout, with SmartSpeed enabled after a hardware
reset, so those PHYs may have the same problem. That is untested on
QCA8327 hardware, so limit this change to QCA8337.

Fixes: b3591c2a3661 ("net: dsa: qca8k: Switch to PHYLINK instead of PHYLIB")
Suggested-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Yongzhao Chen <yongzhao.derek@gmail.com>
Assisted-by: LLM
Link: https://patch.msgid.link/20261013190339.51909-1-yongzhao.derek@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

1 files changed, 58 insertions, 0 deletions

diff --git a/drivers/net/phy/qcom/qca83xx.c b/drivers/net/phy/qcom/qca83xx.c
index bc70ed8efd86..2c4d085bacdb 100644
--- a/drivers/net/phy/qcom/qca83xx.c
+++ b/drivers/net/phy/qcom/qca83xx.c
@@ -92,6 +92,63 @@ static int qca83xx_probe(struct phy_device *phydev)
 	return 0;
 }
 
+static int qca8337_read_status(struct phy_device *phydev)
+{
+	struct at803x_ss_mask ss_mask = {
+		.speed_mask = AT803X_SS_SPEED_MASK,
+		.speed_shift = __bf_shf(AT803X_SS_SPEED_MASK),
+	};
+	int ret, old_link = phydev->link;
+
+	ret = genphy_read_status(phydev);
+	if (ret)
+		return ret;
+
+	/* Keep the state resolved at link-up while the link stays up */
+	if (phydev->autoneg == AUTONEG_ENABLE && old_link && phydev->link)
+		goto out;
+
+	phydev->mdix = ETH_TP_MDI_INVALID;
+
+	/* genphy_read_status() derives speed and duplex from the
+	 * advertisements, which is wrong after a SmartSpeed downshift.
+	 * Use what the PHY resolved instead.
+	 */
+	if (phydev->autoneg == AUTONEG_ENABLE && phydev->autoneg_complete &&
+	    phydev->link) {
+		phydev->speed = SPEED_UNKNOWN;
+		phydev->duplex = DUPLEX_UNKNOWN;
+		phydev->pause = false;
+		phydev->asym_pause = false;
+
+		ret = at803x_read_specific_status(phydev, ss_mask);
+		if (ret)
+			return ret;
+
+		/* Report the link down until speed and duplex are resolved,
+		 * so that the next poll reads them again. Also clear what
+		 * genphy_read_status() read for an up link, as the
+		 * PHY_HALTED path of the state machine does.
+		 */
+		if (phydev->speed == SPEED_UNKNOWN ||
+		    phydev->duplex == DUPLEX_UNKNOWN) {
+			phydev->link = 0;
+			phydev->duplex = DUPLEX_UNKNOWN;
+			phydev->mdix = ETH_TP_MDI_INVALID;
+			phydev->master_slave_state = MASTER_SLAVE_STATE_UNKNOWN;
+			linkmode_zero(phydev->lp_advertising);
+		} else {
+			phy_resolve_aneg_pause(phydev);
+		}
+	}
+
+out:
+	/* MDI-X configuration is not implemented */
+	phydev->mdix_ctrl = ETH_TP_MDI_INVALID;
+
+	return 0;
+}
+
 static int qca83xx_config_init(struct phy_device *phydev)
 {
 	u8 switch_revision;
@@ -220,6 +277,7 @@ static struct phy_driver qca83xx_driver[] = {
 	.flags			= PHY_IS_INTERNAL,
 	.config_init		= qca83xx_config_init,
 	.soft_reset		= genphy_soft_reset,
+	.read_status		= qca8337_read_status,
 	.get_sset_count		= qca83xx_get_sset_count,
 	.get_strings		= qca83xx_get_strings,
 	.get_stats		= qca83xx_get_stats,