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

[Marek Vasut]

On 10/27/24 6:12 AM, Khoa Hoang wrote:
> 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;

Why not use the same trick as u16 adv below here ?

u16 reset = BMCR_RESET;
asix_write_cmd(dev, AX_ACCESS_PHY, 0x03, MII_BMCR, 2, &reset);

> +	asix_write_cmd(dev, AX_ACCESS_PHY, 0x03, MII_BMCR, 2, tmp16);
> +
>   	u16 adv = 0;