linux-kernel - Re: [PATCH net-next 3/6] net: lan966x: Add QUSGMII support for lan966x

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Date:   Thu, 19 May 2022 15:26:23 +0100
From:   "Russell King (Oracle)" <linux@...linux.org.uk>
To:     Maxime Chevallier <maxime.chevallier@...tlin.com>
Cc:     davem@...emloft.net, Rob Herring <robh+dt@...nel.org>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, thomas.petazzoni@...tlin.com,
        Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        Heiner Kallweit <hkallweit1@...il.com>,
        linux-arm-kernel@...ts.infradead.org,
        Richard Cochran <richardcochran@...il.com>,
        Horatiu.Vultur@...rochip.com, Allan.Nielsen@...rochip.com,
        UNGLinuxDriver@...rochip.com
Subject: Re: [PATCH net-next 3/6] net: lan966x: Add QUSGMII support for
 lan966x

Hi,

On Thu, May 19, 2022 at 03:56:44PM +0200, Maxime Chevallier wrote:
> diff --git a/drivers/net/ethernet/microchip/lan966x/lan966x_main.h b/drivers/net/ethernet/microchip/lan966x/lan966x_main.h
> index e6642083ab9e..304c784f48f6 100644
> --- a/drivers/net/ethernet/microchip/lan966x/lan966x_main.h
> +++ b/drivers/net/ethernet/microchip/lan966x/lan966x_main.h
> @@ -452,4 +452,10 @@ static inline void lan_rmw(u32 val, u32 mask, struct lan966x *lan966x,
>  			      gcnt, gwidth, raddr, rinst, rcnt, rwidth));
>  }
>  
> +static inline bool lan966x_is_qsgmii(phy_interface_t mode)
> +{
> +	return (mode == PHY_INTERFACE_MODE_QSGMII) ||
> +	       (mode == PHY_INTERFACE_MODE_QUSGMII);
> +}

Maybe linux/phy.h should provide a helper, something like:

	phy_interface_serdes_lanes()

that returns how many serdes lanes the interface mode uses?

> diff --git a/drivers/net/ethernet/microchip/lan966x/lan966x_phylink.c b/drivers/net/ethernet/microchip/lan966x/lan966x_phylink.c
> index 38a7e95d69b4..96708352f53e 100644
> --- a/drivers/net/ethernet/microchip/lan966x/lan966x_phylink.c
> +++ b/drivers/net/ethernet/microchip/lan966x/lan966x_phylink.c
> @@ -28,11 +28,18 @@ static int lan966x_phylink_mac_prepare(struct phylink_config *config,
>  				       phy_interface_t iface)
>  {
>  	struct lan966x_port *port = netdev_priv(to_net_dev(config->dev));
> +	phy_interface_t serdes_mode = iface;
>  	int err;
>  
>  	if (port->serdes) {
> +		/* As far as the SerDes is concerned, QUSGMII is the same as
> +		 * QSGMII.
> +		 */
> +		if (lan966x_is_qsgmii(iface))
> +			serdes_mode = PHY_INTERFACE_MODE_QSGMII;
> +
>  		err = phy_set_mode_ext(port->serdes, PHY_MODE_ETHERNET,
> -				       iface);
> +				       serdes_mode);

I don't think that the ethernet MAC driver should be changing the
interface mode before passing it down to the generic PHY layer -
phy_set_mode_ext() is defined to take the phy interface mode, and any
aliasing of modes should really be up to the generic PHY driver not
the ethernet MAC driver.

Thanks.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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