Re: [PATCH net] net: lan966x: enforce phy-mode presence

[Vladimir Oltean <olteanv@gmail.com>]

On Thu, Sep 04, 2025 at 01:38:34PM -0700, Rosen Penev wrote:
> The documentation for lan966x states that phy-mode is a required
> property but the code does not enforce this. Add an error check.
> 
> Fixes: db8bcaad5393 ("net: lan966x: add the basic lan966x driver")
> Signed-off-by: Rosen Penev <rosenp@gmail.com>
> ---
>  drivers/net/ethernet/microchip/lan966x/lan966x_main.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/net/ethernet/microchip/lan966x/lan966x_main.c b/drivers/net/ethernet/microchip/lan966x/lan966x_main.c
> index 7001584f1b7a..5d28710f4fd2 100644
> --- a/drivers/net/ethernet/microchip/lan966x/lan966x_main.c
> +++ b/drivers/net/ethernet/microchip/lan966x/lan966x_main.c
> @@ -1199,6 +1199,9 @@ static int lan966x_probe(struct platform_device *pdev)
>  			continue;
>  
>  		phy_mode = fwnode_get_phy_mode(portnp);
> +		if (phy_mode)
> +			goto cleanup_ports;

It's not really great to submit bug fixes without testing them.

/**
 * fwnode_get_phy_mode - Get phy mode for given firmware node
 * @fwnode:	Pointer to the given node
 *
 * The function gets phy interface string from property 'phy-mode' or
 * 'phy-connection-type', and return its index in phy_modes table, or errno in
 * error case.
 */

The test you add will only pass for phy-mode = "", where phy_mode will
be PHY_INTERFACE_MODE_NA. Otherwise, it will be a negative error code,
or a positive phy_interface_t value, and both will result in a "goto
cleanup_ports".

What is the impact of the problem? What happens without your fix?

> +
>  		err = lan966x_probe_port(lan966x, p, phy_mode, portnp);
>  		if (err)
>  			goto cleanup_ports;
> -- 
> 2.51.0
> 
>