[PATCH net-next v0] net: phy: aquantia: poll status register

[Aryan Srivastava]

The system interface connection status register is not immediately
correct upon line side link up. This results in the status being read as
OFF and then transitioning to the correct host side link mode with a
short delay. This results in the phylink framework passing the OFF
status down to all MAC config drivers, resulting in the host side link
being misconfigured, which in turn can lead to link flapping or complete
packet loss in some cases.

Mitigate this by periodically polling the register until it not showing
the OFF state. This will be done every 1ms for 10ms, using the same
poll/timeout as the processor intensive operation reads.

Signed-off-by: Aryan Srivastava <aryan.srivastava@xxxxxxxxxxxxxxxxxxx>
---
 drivers/net/phy/aquantia/aquantia_main.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/net/phy/aquantia/aquantia_main.c b/drivers/net/phy/aquantia/aquantia_main.c
index e982e9ce44a5..d2573982b1e5 100644
--- a/drivers/net/phy/aquantia/aquantia_main.c
+++ b/drivers/net/phy/aquantia/aquantia_main.c
@@ -41,6 +41,7 @@
 #define MDIO_PHYXS_VEND_IF_STATUS_TYPE_XAUI	4
 #define MDIO_PHYXS_VEND_IF_STATUS_TYPE_SGMII	6
 #define MDIO_PHYXS_VEND_IF_STATUS_TYPE_RXAUI	7
+#define MDIO_PHYXS_VEND_IF_STATUS_TYPE_OFF	9
 #define MDIO_PHYXS_VEND_IF_STATUS_TYPE_OCSGMII	10
 
 #define MDIO_AN_VEND_PROV			0xc400
@@ -342,9 +343,18 @@ static int aqr107_read_status(struct phy_device *phydev)
 	if (!phydev->link || phydev->autoneg == AUTONEG_DISABLE)
 		return 0;
 
-	val = phy_read_mmd(phydev, MDIO_MMD_PHYXS, MDIO_PHYXS_VEND_IF_STATUS);
-	if (val < 0)
-		return val;
+	/**
+	 * The status register is not immediately correct on line side link up.
+	 * Poll periodically until it reflects the correct ON state.
+	 */
+	ret = phy_read_mmd_poll_timeout(phydev, MDIO_MMD_PHYXS,
+					MDIO_PHYXS_VEND_IF_STATUS, val,
+					(FIELD_GET(MDIO_PHYXS_VEND_IF_STATUS_TYPE_MASK, val) !=
+					MDIO_PHYXS_VEND_IF_STATUS_TYPE_OFF),
+					AQR107_OP_IN_PROG_SLEEP,
+					AQR107_OP_IN_PROG_TIMEOUT, false);
+	if (ret)
+		return ret;
 
 	switch (FIELD_GET(MDIO_PHYXS_VEND_IF_STATUS_TYPE_MASK, val)) {
 	case MDIO_PHYXS_VEND_IF_STATUS_TYPE_KR:
-- 
2.46.0