[PATCH 1/2] eth: asix88179: Fix ASIX AX88179A PHY hang

[Khoa Hoang]

In the original code, the MII_ADVERTISE register is modified while
auto-negotiation is still in progress, which causes the PHY to lock up
with the ASIX AX88179A.

This patch disables auto-negotiation and resets the PHY before
modifying the MII_ADVERTISE register, then restarts auto-negotiation
afterward. This prevents the PHY from locking up.

Additionally, both AX88179 and AX88179A variants do not appear to
support the ADVERTISE_LPACK (BIT(14)) in the MII_ADVERTISE register,
as setting this bit does not seem to have any effect. While I do not
have access to the AX88179{,A} datasheet, in most Ethernet PHYs, this
bit is reserved as 0, so we should avoid setting it.

Signed-off-by: Khoa Hoang <admin at khoahoang.com>
---
 drivers/usb/eth/asix88179.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/eth/asix88179.c b/drivers/usb/eth/asix88179.c
index 4bd3b9d1..a856aa2d 100644
--- a/drivers/usb/eth/asix88179.c
+++ b/drivers/usb/eth/asix88179.c
@@ -344,14 +344,22 @@ static int asix_basic_reset(struct ueth_data *dev,
 		 AX_MEDIUM_GIGAMODE | AX_MEDIUM_JUMBO_EN;
 	asix_write_cmd(dev, AX_ACCESS_MAC, AX_MEDIUM_STATUS_MODE, 2, 2, tmp16);
 
+	/* Disable auto-negotiation and reset the PHY */
+	*tmp16 = BMCR_RESET;
+	asix_write_cmd(dev, AX_ACCESS_PHY, 0x03, MII_BMCR, 2, tmp16);
+
 	u16 adv = 0;
-	adv = ADVERTISE_ALL | ADVERTISE_CSMA | ADVERTISE_LPACK |
+	adv = ADVERTISE_ALL | ADVERTISE_CSMA |
 	      ADVERTISE_NPAGE | ADVERTISE_PAUSE_ASYM | ADVERTISE_PAUSE_CAP;
 	asix_write_cmd(dev, AX_ACCESS_PHY, 0x03, MII_ADVERTISE, 2, &adv);
 
 	adv = ADVERTISE_1000FULL;
 	asix_write_cmd(dev, AX_ACCESS_PHY, 0x03, MII_CTRL1000, 2, &adv);
 
+	/* Restart auto-negotiation */
+	*tmp16 = BMCR_ANENABLE | BMCR_ANRESTART | BMCR_RESET;
+	asix_write_cmd(dev, AX_ACCESS_PHY, 0x03, MII_BMCR, 2, tmp16);
+
 	return 0;
 }
 
--