linux-kernel - [net-next PATCH 2/2] net: phy: as21xxx: better handle PHY HW reset on soft-reboot

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Message-ID: <20250819164146.1675395-2-ansuelsmth@gmail.com>
Date: Tue, 19 Aug 2025 18:41:41 +0200
From: Christian Marangi <ansuelsmth@...il.com>
To: Christian Marangi <ansuelsmth@...il.com>,
	Andrew Lunn <andrew@...n.ch>,
	Heiner Kallweit <hkallweit1@...il.com>,
	Russell King <linux@...linux.org.uk>,
	"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,
	linux-kernel@...r.kernel.org
Subject: [net-next PATCH 2/2] net: phy: as21xxx: better handle PHY HW reset on soft-reboot

On soft-reboot, with a reset GPIO defined for an Aeonsemi PHY, the
special match_phy_device fails to correctly identify that the PHY
needs to load the firmware again.

This is caused by the fact that PHY ID is read BEFORE the PHY reset
GPIO (if present) is asserted, so we can be in the scenario where the
phydev have the previous PHY ID (with the PHY firmware loaded) but
after reset the generic AS21xxx PHY is present in the PHY ID registers.

To better handle this, skip reading the PHY ID register only for the PHY
that are not AS21xxx (by matching for the Aeonsemi Vendor) and always
read the PHY ID for the other case to handle both firmware already
loaded or an HW reset.

Fixes: 830877d89edc ("net: phy: Add support for Aeonsemi AS21xxx PHYs")
Signed-off-by: Christian Marangi <ansuelsmth@...il.com>
---
 drivers/net/phy/as21xxx.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/net/phy/as21xxx.c b/drivers/net/phy/as21xxx.c
index 92697f43087d..005277360656 100644
--- a/drivers/net/phy/as21xxx.c
+++ b/drivers/net/phy/as21xxx.c
@@ -884,11 +884,12 @@ static int as21xxx_match_phy_device(struct phy_device *phydev,
 	u32 phy_id;
 	int ret;
 
-	/* Skip PHY that are not AS21xxx or already have firmware loaded */
-	if (phydev->c45_ids.device_ids[MDIO_MMD_PCS] != PHY_ID_AS21XXX)
+	/* Skip PHY that are not AS21xxx */
+	if (!phy_id_compare_vendor(phydev->c45_ids.device_ids[MDIO_MMD_PCS],
+				   PHY_VENDOR_AEONSEMI))
 		return genphy_match_phy_device(phydev, phydrv);
 
-	/* Read PHY ID to handle firmware just loaded */
+	/* Read PHY ID to handle firmware loaded or HW reset */
 	ret = phy_read_mmd(phydev, MDIO_MMD_PCS, MII_PHYSID1);
 	if (ret < 0)
 		return ret;
-- 
2.50.0