Re: assert in phylink.c with lan7801 and dp83tc811 since kernel 6.18

[Andrew Lunn <andrew@lunn.ch>]

> So for me it somewhere happens in phylink_validate_mac_and_pcs()

I was expecting to see more debug output, but reading the code, i was
also thinking we need to look at phylink_validate_mac_and_pcs().

You are going in the correct direction putting lots of printk() in the
code. We need to find where it returns EINVAL:

static int phylink_validate_mac_and_pcs(struct phylink *pl,
					unsigned long *supported,
					struct phylink_link_state *state)
{
	struct phylink_pcs *pcs = NULL;
	unsigned long capabilities;
	int ret;

	/* Get the PCS for this interface mode */
	if (pl->mac_ops->mac_select_pcs) {
		pcs = pl->mac_ops->mac_select_pcs(pl->config, state->interface);
		if (IS_ERR(pcs))
			return PTR_ERR(pcs);
Possibly.


	}

	if (pcs) {
		/* The PCS, if present, must be setup before phylink_create()
		 * has been called. If the ops is not initialised, print an
		 * error and backtrace rather than oopsing the kernel.
		 */
		if (!pcs->ops) {
			phylink_err(pl, "interface %s: uninitialised PCS\n",
				    phy_modes(state->interface));
			dump_stack();
We don't see a stack dump, so not here.

			return -EINVAL;
		}

		/* Ensure that this PCS supports the interface which the MAC
		 * returned it for. It is an error for the MAC to return a PCS
		 * that does not support the interface mode.
		 */
		if (!phy_interface_empty(pcs->supported_interfaces) &&
		    !test_bit(state->interface, pcs->supported_interfaces)) {
			phylink_err(pl, "MAC returned PCS which does not support %s\n",
				    phy_modes(state->interface));
No error message....				    
			return -EINVAL;
		}

		/* Validate the link parameters with the PCS */
		if (pcs->ops->pcs_validate) {
			ret = pcs->ops->pcs_validate(pcs, supported, state);
			if (ret < 0 || phylink_is_empty_linkmode(supported))
Could be...			
				return -EINVAL;

			/* Ensure the advertising mask is a subset of the
			 * supported mask.
			 */
			linkmode_and(state->advertising, state->advertising,
				     supported);
		}
	}

	/* Then validate the link parameters with the MAC */
	if (pl->mac_ops->mac_get_caps)
		capabilities = pl->mac_ops->mac_get_caps(pl->config,
							 state->interface);
	else
		capabilities = pl->config->mac_capabilities;

	phylink_validate_mask_caps(supported, state, capabilities);

	return phylink_is_empty_linkmode(supported) ? -EINVAL : 0;

Also possible.

}

In the end, we are probably going to find that what the MAC says its
capabilities are don't match what the PCS says it can do.

Thinking about that, it says phy mode RGMII. You generally don't use a
PCS with RGMII, so that is suspicious.

    Andrew