linux-kernel - Re: [PATCH v2] lan743x: add virtual PHY for PHY-less devices

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Message-ID: <YAtMw5Yk1QYp28rJ@lunn.ch>
Date:   Fri, 22 Jan 2021 23:08:03 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     Sergej Bauer <sbauer@...ckbox.su>
Cc:     netdev@...r.kernel.org, f.fainelli@...il.com,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Bryan Whitehead <bryan.whitehead@...rochip.com>,
        UNGLinuxDriver@...rochip.com,
        Simon Horman <simon.horman@...ronome.com>,
        Mark Einon <mark.einon@...il.com>,
        Madalin Bucur <madalin.bucur@....nxp.com>,
        Arnd Bergmann <arnd@...db.de>,
        Masahiro Yamada <masahiroy@...nel.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] lan743x: add virtual PHY for PHY-less devices

On Sat, Jan 23, 2021 at 12:42:41AM +0300, Sergej Bauer wrote:
> From: sbauer@...ckbox.su
> 
> v1->v2:
> 	switch to using of fixed_phy as was suggested by Andrew and Florian
> 	also features-related parts are removed

This is not using fixed_phy, at least not in the normal way.

Take a look at bgmac_phy_connect_direct() for example. Call
fixed_phy_register(), and then phy_connect_direct() with the
phydev. End of story. Done.

> +int lan743x_set_link_ksettings(struct net_device *netdev,
> +			       const struct ethtool_link_ksettings *cmd)
> +{
> +	if (!netdev->phydev)
> +		return -ENETDOWN;
> +
> +	return phy_is_pseudo_fixed_link(netdev->phydev) ?
> +			lan743x_set_virtual_link_ksettings(netdev, cmd)
> +			: phy_ethtool_set_link_ksettings(netdev, cmd);
> +}

There should not be any need to do something different. The whole
point of fixed_phy is it looks like a PHY. So calling
phy_ethtool_set_link_ksettings() should work, nothing special needed.

> @@ -1000,8 +1005,10 @@ static void lan743x_phy_close(struct lan743x_adapter *adapter)
>  	struct net_device *netdev = adapter->netdev;
>  
>  	phy_stop(netdev->phydev);
> -	phy_disconnect(netdev->phydev);
> -	netdev->phydev = NULL;
> +	if (phy_is_pseudo_fixed_link(netdev->phydev))
> +		lan743x_virtual_phy_disconnect(netdev->phydev);
> +	else
> +		phy_disconnect(netdev->phydev);

phy_disconnect() should work. You might want to call
fixed_phy_unregister() afterwards, so you do not leak memory.

> +		if (phy_is_pseudo_fixed_link(phydev)) {
> +			ret = phy_connect_direct(netdev, phydev,
> +						 lan743x_virtual_phy_status_change,
> +						 PHY_INTERFACE_MODE_MII);
> +		} else {
> +			ret = phy_connect_direct(netdev, phydev,
> +						 lan743x_phy_link_status_change,

There should not be any need for a special link change
callback. lan743x_phy_link_status_change() should work fine, the MAC
should have no idea it is using a fixed_phy.

> +						 PHY_INTERFACE_MODE_GMII);
> +		}
> +
>  		if (ret)
>  			goto return_error;
>  	}
> @@ -1031,6 +1049,15 @@ static int lan743x_phy_open(struct lan743x_adapter *adapter)
>  	/* MAC doesn't support 1000T Half */
>  	phy_remove_link_mode(phydev, ETHTOOL_LINK_MODE_1000baseT_Half_BIT);
>  
> +	if (phy_is_pseudo_fixed_link(phydev)) {
> +		phy_remove_link_mode(phydev, ETHTOOL_LINK_MODE_TP_BIT);
> +		linkmode_set_bit(ETHTOOL_LINK_MODE_10baseT_Full_BIT,
> +				 phydev->supported);
> +		linkmode_set_bit(ETHTOOL_LINK_MODE_100baseT_Full_BIT,
> +				 phydev->supported);
> +		phy_advertise_supported(phydev);
> +	}

The fixed PHY driver will set these bits depending on the speed it has
been configured for. No need to change them. The MAC should also not
care if it is TP, AUI, Fibre or smoke signals.

     Andrew