[...]

> +static void airoha_mac_config(struct phylink_config *config, unsigned int mode,
> +			      const struct phylink_link_state *state)
> +{
> +}
> +
> +static void airoha_mac_link_up(struct phylink_config *config, struct phy_device *phy,
> +			       unsigned int mode, phy_interface_t interface,
> +			       int speed, int duplex, bool tx_pause, bool rx_pause)
> +{
> +	struct airoha_gdm_dev *dev = container_of(config, struct airoha_gdm_dev,
> +						  phylink_config);
> +	struct airoha_gdm_port *port = dev->port;
> +	struct airoha_eth *eth = dev->eth;
> +	u32 frag_size_tx, frag_size_rx;
> +	u32 mask, val;
> +
> +	/* TX/RX frag is configured only for GDM4 */
> +	if (port->id != AIROHA_GDM4_IDX)
> +		return;
> +
> +	switch (speed) {
> +	case SPEED_10000:
> +	case SPEED_5000:
> +		frag_size_tx = 8;
> +		frag_size_rx = 8;
> +		break;
> +	case SPEED_2500:
> +		frag_size_tx = 2;
> +		frag_size_rx = 1;
> +		break;
> +	default:
> +		frag_size_tx = 1;
> +		frag_size_rx = 0;
> +	}
> +
> +	spin_lock(&port->lock);

Using a spin_lock seems overkill here to me since airoha_mac_link_up()
run in the process context and the spin_lock you are acquiring here
was just used for stats. Since mac_link_up is running in some cases
acquiring RTNL, I guess you can even do something like:

	bool rtnl = rtnl_is_locked();

	if (!rtnl)
		rtnl_lock();
	...
	if (!rtnl)
		rtnl_unlock();

Regards,
Lorenzo

> +
> +	/* Configure TX/RX frag based on speed */
> +	if (dev->nbq == 1) {
> +		mask = GDM4_SGMII1_TX_FRAG_SIZE_MASK;
> +		val = FIELD_PREP(GDM4_SGMII1_TX_FRAG_SIZE_MASK,
> +				 frag_size_tx);
> +	}  else {
> +		mask = GDM4_SGMII0_TX_FRAG_SIZE_MASK;
> +		val = FIELD_PREP(GDM4_SGMII0_TX_FRAG_SIZE_MASK,
> +				 frag_size_tx);
> +	}
> +	airoha_fe_rmw(eth, REG_FE_GDM4_TMBI_FRAG, mask, val);
> +
> +	if (dev->nbq == 1) {
> +		mask = GDM4_SGMII1_RX_FRAG_SIZE_MASK;
> +		val = FIELD_PREP(GDM4_SGMII1_RX_FRAG_SIZE_MASK,
> +				 frag_size_rx);
> +	} else {
> +		mask = GDM4_SGMII0_RX_FRAG_SIZE_MASK;
> +		val = FIELD_PREP(GDM4_SGMII0_RX_FRAG_SIZE_MASK,
> +				 frag_size_rx);
> +	}
> +	airoha_fe_rmw(eth, REG_FE_GDM4_RMBI_FRAG, mask, val);
> +
> +	spin_unlock(&port->lock);
> +}
> +
> +/* Nothing to do in MAC, everything is handled in PCS */
> +static void airoha_mac_link_down(struct phylink_config *config, unsigned int mode,
> +				 phy_interface_t interface)
> +{
> +}
> +
> +static const struct phylink_mac_ops airoha_phylink_ops = {
> +	.mac_config = airoha_mac_config,
> +	.mac_link_up = airoha_mac_link_up,
> +	.mac_link_down = airoha_mac_link_down,
> +};
> +
> +static int airoha_fill_available_pcs(struct phylink_config *config,
> +				     struct phylink_pcs **available_pcs,
> +				     unsigned int num_possible_pcs)
> +{
> +	struct device *dev = config->dev;
> +
> +	return fwnode_phylink_pcs_parse(dev_fwnode(dev), available_pcs,
> +					num_possible_pcs);
> +}
> +
> +static int airoha_setup_phylink(struct net_device *netdev)
> +{
> +	struct airoha_gdm_dev *dev = netdev_priv(netdev);
> +	struct device_node *np = netdev->dev.of_node;
> +	struct airoha_gdm_port *port = dev->port;
> +	struct phylink_config *config;
> +	phy_interface_t phy_mode;
> +	struct phylink *phylink;
> +	int err;
> +
> +	err = of_get_phy_mode(np, &phy_mode);
> +	if (err) {
> +		dev_err(&netdev->dev, "incorrect phy-mode\n");
> +		return err;
> +	}
> +
> +	config = &dev->phylink_config;
> +	config->dev = &netdev->dev;
> +	config->type = PHYLINK_NETDEV;
> +
> +	/*
> +	 * GDM1 only supports internal for Embedded Switch
> +	 * and doesn't require a PCS.
> +	 */
> +	if (port->id == AIROHA_GDM1_IDX) {
> +		config->mac_capabilities = MAC_ASYM_PAUSE | MAC_SYM_PAUSE |
> +					   MAC_10000FD;
> +
> +		__set_bit(PHY_INTERFACE_MODE_INTERNAL,
> +			  config->supported_interfaces);
> +	} else {
> +		config->mac_capabilities = MAC_ASYM_PAUSE | MAC_SYM_PAUSE |
> +					   MAC_10 | MAC_100 | MAC_1000 |
> +					   MAC_2500FD | MAC_5000FD | MAC_10000FD;
> +
> +		config->num_possible_pcs = fwnode_phylink_pcs_count(dev_fwnode(config->dev));
> +		config->fill_available_pcs = airoha_fill_available_pcs;
> +
> +		__set_bit(PHY_INTERFACE_MODE_SGMII,
> +			  config->supported_interfaces);
> +		__set_bit(PHY_INTERFACE_MODE_1000BASEX,
> +			  config->supported_interfaces);
> +		__set_bit(PHY_INTERFACE_MODE_2500BASEX,
> +			  config->supported_interfaces);
> +		__set_bit(PHY_INTERFACE_MODE_10GBASER,
> +			  config->supported_interfaces);
> +		__set_bit(PHY_INTERFACE_MODE_USXGMII,
> +			  config->supported_interfaces);
> +
> +		phy_interface_copy(config->pcs_interfaces,
> +				   config->supported_interfaces);
> +	}
> +
> +	phylink = phylink_create(config, of_fwnode_handle(np),
> +				 phy_mode, &airoha_phylink_ops);
> +	if (IS_ERR(phylink))
> +		return PTR_ERR(phylink);
> +
> +	dev->phylink = phylink;
> +
> +	return 0;
> +}
> +
>  static int airoha_alloc_gdm_device(struct airoha_eth *eth,
>  				   struct airoha_gdm_port *port,
>  				   int nbq, struct device_node *np)
> @@ -3231,7 +3411,7 @@ static int airoha_alloc_gdm_device(struct airoha_eth *eth,
>  	dev->nbq = nbq;
>  	port->devs[index] = dev;
>  
> -	return 0;
> +	return airoha_setup_phylink(netdev);
>  }
>  
>  static int airoha_alloc_gdm_port(struct airoha_eth *eth,
> @@ -3266,7 +3446,7 @@ static int airoha_alloc_gdm_port(struct airoha_eth *eth,
>  		return -ENOMEM;
>  
>  	port->id = id;
> -	spin_lock_init(&port->stats_lock);
> +	spin_lock_init(&port->lock);
>  	eth->ports[p] = port;
>  
>  	err = airoha_metadata_dst_alloc(port);
> @@ -3457,6 +3637,8 @@ static int airoha_probe(struct platform_device *pdev)
>  			netdev = netdev_from_priv(dev);
>  			if (netdev->reg_state == NETREG_REGISTERED)
>  				unregister_netdev(netdev);
> +			if (dev->phylink)
> +				phylink_destroy(dev->phylink);
>  			of_node_put(netdev->dev.of_node);
>  		}
>  		airoha_metadata_dst_free(port);
> @@ -3493,6 +3675,7 @@ static void airoha_remove(struct platform_device *pdev)
>  
>  			netdev = netdev_from_priv(dev);
>  			unregister_netdev(netdev);
> +			phylink_destroy(dev->phylink);
>  			of_node_put(netdev->dev.of_node);
>  		}
>  		airoha_metadata_dst_free(port);
> diff --git a/drivers/net/ethernet/airoha/airoha_eth.h b/drivers/net/ethernet/airoha/airoha_eth.h
> index 46b1c31939de..a6fef1777c7b 100644
> --- a/drivers/net/ethernet/airoha/airoha_eth.h
> +++ b/drivers/net/ethernet/airoha/airoha_eth.h
> @@ -554,6 +554,9 @@ struct airoha_gdm_dev {
>  	int nbq;
>  
>  	struct airoha_hw_stats stats;
> +
> +	struct phylink *phylink;
> +	struct phylink_config phylink_config;
>  };
>  
>  struct airoha_gdm_port {
> @@ -561,8 +564,8 @@ struct airoha_gdm_port {
>  	int id;
>  	int users;
>  
> -	/* protect concurrent hw_stats accesses */
> -	spinlock_t stats_lock;
> +	/* protect concurrent hw_stats and frag register accesses */
> +	spinlock_t lock;
>  
>  	struct metadata_dst *dsa_meta[AIROHA_MAX_DSA_PORTS];
>  };
> diff --git a/drivers/net/ethernet/airoha/airoha_regs.h b/drivers/net/ethernet/airoha/airoha_regs.h
> index 436f3c8779c1..6ad91ca6dcd3 100644
> --- a/drivers/net/ethernet/airoha/airoha_regs.h
> +++ b/drivers/net/ethernet/airoha/airoha_regs.h
> @@ -358,6 +358,18 @@
>  #define IP_FRAGMENT_PORT_MASK		GENMASK(8, 5)
>  #define IP_FRAGMENT_NBQ_MASK		GENMASK(4, 0)
>  
> +#define REG_FE_GDM4_TMBI_FRAG		0x2028
> +#define GDM4_SGMII1_TX_WEIGHT_MASK	GENMASK(31, 26)
> +#define GDM4_SGMII1_TX_FRAG_SIZE_MASK	GENMASK(25, 16)
> +#define GDM4_SGMII0_TX_WEIGHT_MASK	GENMASK(15, 10)
> +#define GDM4_SGMII0_TX_FRAG_SIZE_MASK	GENMASK(9, 0)
> +
> +#define REG_FE_GDM4_RMBI_FRAG		0x202c
> +#define GDM4_SGMII1_RX_WEIGHT_MASK	GENMASK(31, 26)
> +#define GDM4_SGMII1_RX_FRAG_SIZE_MASK	GENMASK(25, 16)
> +#define GDM4_SGMII0_RX_WEIGHT_MASK	GENMASK(15, 10)
> +#define GDM4_SGMII0_RX_FRAG_SIZE_MASK	GENMASK(9, 0)
> +
>  #define REG_MC_VLAN_EN			0x2100
>  #define MC_VLAN_EN_MASK			BIT(0)
>  
> -- 
> 2.53.0
>