Re: [PATCH] usbnet_link_change() fails to call netif_carrier_on()

From: Andrew Lunn
Date: Tue Nov 19 2024 - 11:21:09 EST


On Tue, Nov 19, 2024 at 02:46:59PM +0100, Krzysztof Hałasa wrote:
> Hi,
>
> ASIX AX88772B based USB 10/100 Ethernet adapter doesn't come
> up ("carrier off"), despite the built-in 100BASE-FX PHY positive link
> indication.
>
> The problem appears to be in usbnet.c framework:
>
> void usbnet_link_change(struct usbnet *dev, bool link, bool need_reset)
> {
> /* update link after link is reseted */
> if (link && !need_reset)
> netif_carrier_on(dev->net);
> else
> netif_carrier_off(dev->net);
>
> if (need_reset && link)
> usbnet_defer_kevent(dev, EVENT_LINK_RESET);
> else
> usbnet_defer_kevent(dev, EVENT_LINK_CHANGE);
> }

static int ax88772_phylink_setup(struct usbnet *dev)
{
struct asix_common_private *priv = dev->driver_priv;
phy_interface_t phy_if_mode;
struct phylink *phylink;

priv->phylink_config.dev = &dev->net->dev;
priv->phylink_config.type = PHYLINK_NETDEV;
priv->phylink_config.mac_capabilities = MAC_SYM_PAUSE | MAC_ASYM_PAUSE |
MAC_10 | MAC_100;

etc.

This device is using phylink to manage the PHY. phylink will than
manage the carrier. It assumes it is solely responsible for the
carrier. So i think your fix is wrong. You probably should be removing
all code in this driver which touches the carrier.

Andrew