[PATCH net-next v4 3/4] microchip: lan865x: enable PHY interrupt via virtual IRQ

[Parthiban Veerasooran <parthiban.veerasooran@microchip.com>]

The LAN865X integrates the PHY directly into the MAC-PHY SPI device.
The PHY has no dedicated interrupt line; its interrupt is always
delivered as the PHYINT bit in STATUS0.

Pass the OA_TC6_PHY_INT quirk flag to oa_tc6_init() to enable the
virtual IRQ infrastructure. This lets phylib operate in interrupt mode
and drives the PHY driver's config_intr/handle_interrupt callbacks for
the LAN865X internal PHY.

This completes the collision-detection fix started in "net: phy:
microchip_t1s: fix collision detection on PLCA status change"; without
this patch (and its prerequisite, "net: ethernet: oa_tc6: deliver the
PHY interrupt to phylib"), LAN865X stays on that commit's polling-based
CDEN synchronization/fallback instead of tracking PLCA transitions
dynamically.

CDEN is synchronized to the live PLCA status when lan86xx_config_intr()
runs during phy_enable_interrupts(), then tracked on each subsequent
PLCA transition via lan86xx_handle_interrupt(). This PHY interrupt path
is critical for keeping CDEN correct across PLCA transitions.

Fixes: 78341049fbcd ("net: phy: microchip_t1s: configure collision detection based on PLCA mode")
Signed-off-by: Parthiban Veerasooran <parthiban.veerasooran@microchip.com>
---
 drivers/net/ethernet/microchip/lan865x/lan865x.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/microchip/lan865x/lan865x.c b/drivers/net/ethernet/microchip/lan865x/lan865x.c
index 127afb9e9f14..d47560f9847d 100644
--- a/drivers/net/ethernet/microchip/lan865x/lan865x.c
+++ b/drivers/net/ethernet/microchip/lan865x/lan865x.c
@@ -332,6 +332,7 @@ static const struct net_device_ops lan865x_netdev_ops = {
 
 static int lan865x_probe(struct spi_device *spi)
 {
+	struct oa_tc6_quirks tc6_quirks = {};
 	struct net_device *netdev;
 	struct lan865x_priv *priv;
 	int ret;
@@ -346,7 +347,8 @@ static int lan865x_probe(struct spi_device *spi)
 	spi_set_drvdata(spi, priv);
 	INIT_WORK(&priv->multicast_work, lan865x_multicast_work_handler);
 
-	priv->tc6 = oa_tc6_init(spi, netdev, NULL);
+	tc6_quirks.quirk_flags = OA_TC6_PHY_INT;
+	priv->tc6 = oa_tc6_init(spi, netdev, &tc6_quirks);
 	if (IS_ERR(priv->tc6)) {
 		ret = PTR_ERR(priv->tc6);
 		goto free_netdev;
-- 
2.43.0