[PATCH RESEND v3] net: airoha_eth: fix mt7531 mdio related initialization bug

[Tom Rini]

On Tue, Jun 16, 2026 at 08:38:45AM +0300, Mikhail Kshevetskiy wrote:
> Private data isn't ready during bind time. The call of dev_get_priv()
> function will return NULL. Thus we can't save mdio device pointer and
> use it later during probe.
> 
> To solve an issue, we will move mt7531 mdio device binding to the probing
> function of 'airoha-eth' driver.
> 
> All GDM ports (except of GDM1) are connected directly to their PHYs, so
> corresponding mdio bus will be automatically probed during PHY setup.
> 
> GDM1 ports differ from other GDM ports. It connected to the airoha switch
> device. The mt7531 mdio bus is used to manage link state of airoha switch
> device ports (LAN ports 1-4 corresponds to PHYs 0x09-0x0C). Therefore,
> manual probing of mt7531 mdio bus is required to be able set/query states
> of corresponding LAN ports.
> 
> Fixes: 96d9e7c46425 ("net: airoha: use mt7531 mdio for GDM1")
> Signed-off-by: Mikhail Kshevetskiy <mikhail.kshevetskiy at iopsys.eu>

This is fixing something introduced for the upcoming release, Jerome do
you want to take it (or have feedback on it?) or should I? Thanks!

> ---
> Changes v2:
>  * small refactoring
> 
> Changes v3:
>  * Move mt7531 mdio bus initialization function before it's first usage.
>  * Probe mt7531 mdio bus for GDM1 port, but not for other GDM port.
>  * Add an explanation why mt7531 mdio bus must be probed for GDM1 only
> ---
>  drivers/net/airoha_eth.c | 78 ++++++++++++++++++++++++----------------
>  1 file changed, 48 insertions(+), 30 deletions(-)
> 
> diff --git a/drivers/net/airoha_eth.c b/drivers/net/airoha_eth.c
> index 84ee9b2ad76..e5d39b95cc5 100644
> --- a/drivers/net/airoha_eth.c
> +++ b/drivers/net/airoha_eth.c
> @@ -845,11 +845,45 @@ static int airoha_alloc_gdm_port(struct udevice *dev, ofnode node)
>  					    (ulong)eth, node, &gdm_dev);
>  }
>  
> +static struct udevice *airoha_switch_mdio_init(struct udevice *dev)
> +{
> +	struct airoha_eth_soc_data *data = (void *)dev_get_driver_data(dev);
> +	ofnode switch_node, mdio_node;
> +	struct udevice *mdio_dev;
> +	int ret;
> +
> +	if (!CONFIG_IS_ENABLED(MDIO_MT7531_MMIO))
> +		return NULL;
> +
> +	switch_node = ofnode_by_compatible(ofnode_null(),
> +					   data->switch_compatible);
> +	if (!ofnode_valid(switch_node)) {
> +		debug("Warning: missing airoha switch node\n");
> +		return ERR_PTR(-EINVAL);
> +	}
> +
> +	mdio_node = ofnode_find_subnode(switch_node, "mdio");
> +	if (!ofnode_valid(mdio_node)) {
> +		debug("Warning: missing airoha switch mdio subnode\n");
> +		return ERR_PTR(-EINVAL);
> +	}
> +
> +	ret = device_bind_driver_to_node(dev, "mt7531-mdio-mmio", "mt7531-mdio",
> +					 mdio_node, &mdio_dev);
> +	if (ret) {
> +		debug("Warning: failed to bind airoha switch mdio\n");
> +		return ERR_PTR(ret);
> +	}
> +
> +	return mdio_dev;
> +}
> +
>  static int airoha_eth_probe(struct udevice *dev)
>  {
>  	struct airoha_eth_soc_data *data = (void *)dev_get_driver_data(dev);
>  	struct airoha_eth *eth = dev_get_priv(dev);
>  	struct regmap *scu_regmap;
> +	struct udevice *mdio_dev;
>  	ofnode node;
>  	int i, ret;
>  
> @@ -908,10 +942,10 @@ static int airoha_eth_probe(struct udevice *dev)
>  	if (ret)
>  		return ret;
>  
> -	if (eth->switch_mdio_dev) {
> -		if (!device_probe(eth->switch_mdio_dev))
> -			debug("Warning: failed to probe airoha switch mdio\n");
> -	}
> +	/* Airoha switch mdio PHYs maybe used by several GDM devices */
> +	mdio_dev = airoha_switch_mdio_init(dev);
> +	if (!IS_ERR_OR_NULL(mdio_dev))
> +		eth->switch_mdio_dev = mdio_dev;
>  
>  	ofnode_for_each_subnode(node, dev_ofnode(dev)) {
>  		if (!ofnode_device_is_compatible(node, "airoha,eth-mac"))
> @@ -957,6 +991,16 @@ static int airoha_eth_port_probe(struct udevice *dev)
>  #else
>  		return -EINVAL;
>  #endif
> +	} else {
> +		/*
> +		 * GDM1 device connected to airoha switch. Probe airoha switch
> +		 * mdio to be able set/query states of corresponding LAN ports.
> +		 */
> +		ret = device_probe(eth->switch_mdio_dev);
> +		if (ret) {
> +			debug("Warning: failed to probe airoha switch mdio\n");
> +			eth->switch_mdio_dev = NULL;
> +		}
>  	}
>  
>  	return 0;
> @@ -1202,38 +1246,12 @@ static int arht_eth_write_hwaddr(struct udevice *dev)
>  
>  static int airoha_eth_bind(struct udevice *dev)
>  {
> -	struct airoha_eth_soc_data *data = (void *)dev_get_driver_data(dev);
> -	struct airoha_eth *eth = dev_get_priv(dev);
> -	ofnode switch_node, mdio_node;
> -	int ret;
> -
>  	/*
>  	 * Force Probe as we set the Main ETH driver as misc
>  	 * to register multiple eth port for each GDM
>  	 */
>  	dev_or_flags(dev, DM_FLAG_PROBE_AFTER_BIND);
>  
> -	if (!CONFIG_IS_ENABLED(MDIO_MT7531_MMIO))
> -		return 0;
> -
> -	switch_node = ofnode_by_compatible(ofnode_null(),
> -					   data->switch_compatible);
> -	if (!ofnode_valid(switch_node)) {
> -		debug("Warning: missing switch node\n");
> -		return 0;
> -	}
> -
> -	mdio_node = ofnode_find_subnode(switch_node, "mdio");
> -	if (!ofnode_valid(mdio_node)) {
> -		debug("Warning: missing mdio node\n");
> -		return 0;
> -	}
> -
> -	ret = device_bind_driver_to_node(dev, "mt7531-mdio-mmio", "mt7531-mdio",
> -					 mdio_node, &eth->switch_mdio_dev);
> -	if (ret)
> -		debug("Warning: failed to bind mdio controller\n");
> -
>  	return 0;
>  }
>  
> -- 
> 2.53.0
> 

-- 
Tom
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