Re: [PATCH net v2 3/3] net: phy: don't try to setup PHY-driven SFP cages when using genphy

[Nicolai Buchwitz <nb@tipi-net.de>]

On 1.6.2026 10:40, Maxime Chevallier wrote:
> We don't have support for PHY-driver SFP cages with the genphy code.
> 
> On top of that, it was found by sashiko that running
> sfp_bus_add_upstream() for genphy deadlocks, as for genphy the PHY
> probing runs under RTNL, which isn't the case for non-genphy drivers.
> 
> This problem was reproduced, and does lead to a deadlock on RTNL.
> 
> Before the blamed commit, the phy_sfp_probe() call was made by
> individual PHY drivers, so there was no way to get to the SFP probing
> path when using genphy.
> 
> Let's therefore only run phy_sfp_probe when not using genphy.
> 
> Fixes: bad869b5e41a ("net: phy: Only rely on phy_port for PHY-driven 
> SFP")
> Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
> ---
>  drivers/net/phy/phy_device.c | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/phy/phy_device.c 
> b/drivers/net/phy/phy_device.c
> index a171cbe2a74a..8eace58e9f12 100644
> --- a/drivers/net/phy/phy_device.c
> +++ b/drivers/net/phy/phy_device.c
> @@ -3512,9 +3512,14 @@ static int phy_setup_ports(struct phy_device 
> *phydev)
>  	if (ret)
>  		return ret;
> 
> -	ret = phy_sfp_probe(phydev);
> -	if (ret)
> -		goto out;
> +	/* We don't support SFP with genphy drivers. Also, genphy driver 
> binding
> +	 * occurs with RTNL help, wich will deadlock the 
> sfp_bus_add_upstream().
> +	 */
> +	if (!phydev->is_genphy_driven) {
> +		ret = phy_sfp_probe(phydev);
> +		if (ret)
> +			goto out;
> +	}
> 
>  	if (phydev->n_ports < phydev->max_n_ports) {
>  		ret = phy_default_setup_single_port(phydev);

Reviewed-by: Nicolai Buchwitz <nb@tipi-net.de>

Thanks
Nicolai