Subject: Re: [PATCH net-next 2/7] net: dsa: felix: support half-duplex link modes

From: Russell King - ARM Linux admin <[email-masked]>
Date: Thu, 25 Jun 2020 17:30:13 +0100

On Thu, Jun 25, 2020 at 06:23:26PM +0300, Vladimir Oltean wrote:
> From: Vladimir Oltean <[email-masked]>
> 
> Ping tested:
> 
>   [   11.808455] mscc_felix 0000:00:00.5 swp0: Link is Up - 1Gbps/Full - flow control rx/tx
>   [   11.816497] IPv6: ADDRCONF(NETDEV_CHANGE): swp0: link becomes ready
> 
>   [root@LS1028ARDB ~] # ethtool -s swp0 advertise 0x4
>   [   18.844591] mscc_felix 0000:00:00.5 swp0: Link is Down
>   [   22.048337] mscc_felix 0000:00:00.5 swp0: Link is Up - 100Mbps/Half - flow control off
> 
>   [root@LS1028ARDB ~] # ip addr add 192.168.1.1/24 dev swp0
> 
>   [root@LS1028ARDB ~] # ping 192.168.1.2
>   PING 192.168.1.2 (192.168.1.2): 56 data bytes
>   (...)
>   ^C--- 192.168.1.2 ping statistics ---
>   3 packets transmitted, 3 packets received, 0% packet loss
>   round-trip min/avg/max = 0.383/0.611/1.051 ms
> 
>   [root@LS1028ARDB ~] # ethtool -s swp0 advertise 0x10
>   [  355.637747] mscc_felix 0000:00:00.5 swp0: Link is Down
>   [  358.788034] mscc_felix 0000:00:00.5 swp0: Link is Up - 1Gbps/Half - flow control off
> 
>   [root@LS1028ARDB ~] # ping 192.168.1.2
>   PING 192.168.1.2 (192.168.1.2): 56 data bytes
>   (...)
>   ^C
>   --- 192.168.1.2 ping statistics ---
>   16 packets transmitted, 16 packets received, 0% packet loss
>   round-trip min/avg/max = 0.301/0.384/1.138 ms
> 
> Signed-off-by: Vladimir Oltean <[email-masked]>
> Reviewed-by: Florian Fainelli <[email-masked]>

Ping isn't really a good test of whether half duplex mode is operating
correctly.  However, apart from that detail, and as this reflects the
functionality I implemented with the LX2160A version of this PCS:

Reviewed-by: Russell King <[email-masked]>

> ---
> Repost of:
> https://patchwork.ozlabs.org/project/netdev/patch/[email-masked]/
> Changed:
> In the "forced link" scenario (not previously tested, just in-band), we
> need to configure half duplex through the IF_MODE register, not BMCR.
> 
>  drivers/net/dsa/ocelot/felix.c         |  4 +++-
>  drivers/net/dsa/ocelot/felix_vsc9959.c | 24 ++++++++++++++----------
>  include/linux/fsl/enetc_mdio.h         |  1 +
>  3 files changed, 18 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/net/dsa/ocelot/felix.c b/drivers/net/dsa/ocelot/felix.c
> index 25046777c993..25b340e0a6dd 100644
> --- a/drivers/net/dsa/ocelot/felix.c
> +++ b/drivers/net/dsa/ocelot/felix.c
> @@ -194,13 +194,15 @@ static void felix_phylink_validate(struct dsa_switch *ds, int port,
>  		return;
>  	}
>  
> -	/* No half-duplex. */
>  	phylink_set_port_modes(mask);
>  	phylink_set(mask, Autoneg);
>  	phylink_set(mask, Pause);
>  	phylink_set(mask, Asym_Pause);
> +	phylink_set(mask, 10baseT_Half);
>  	phylink_set(mask, 10baseT_Full);
> +	phylink_set(mask, 100baseT_Half);
>  	phylink_set(mask, 100baseT_Full);
> +	phylink_set(mask, 1000baseT_Half);
>  	phylink_set(mask, 1000baseT_Full);
>  
>  	if (state->interface == PHY_INTERFACE_MODE_INTERNAL ||
> diff --git a/drivers/net/dsa/ocelot/felix_vsc9959.c b/drivers/net/dsa/ocelot/felix_vsc9959.c
> index 3269c76b59ff..c1220b488f9c 100644
> --- a/drivers/net/dsa/ocelot/felix_vsc9959.c
> +++ b/drivers/net/dsa/ocelot/felix_vsc9959.c
> @@ -817,12 +817,9 @@ static void vsc9959_pcs_init_sgmii(struct phy_device *pcs,
>  
>  		phy_write(pcs, MII_BMCR, BMCR_ANRESTART | BMCR_ANENABLE);
>  	} else {
> +		u16 if_mode = ENETC_PCS_IF_MODE_SGMII_EN;
>  		int speed;
>  
> -		if (state->duplex == DUPLEX_HALF) {
> -			phydev_err(pcs, "Half duplex not supported\n");
> -			return;
> -		}
>  		switch (state->speed) {
>  		case SPEED_1000:
>  			speed = ENETC_PCS_SPEED_1000;
> @@ -841,10 +838,11 @@ static void vsc9959_pcs_init_sgmii(struct phy_device *pcs,
>  			return;
>  		}
>  
> -		phy_write(pcs, ENETC_PCS_IF_MODE,
> -			  ENETC_PCS_IF_MODE_SGMII_EN |
> -			  ENETC_PCS_IF_MODE_SGMII_SPEED(speed));
> +		if_mode |= ENETC_PCS_IF_MODE_SGMII_SPEED(speed);
> +		if (state->duplex == DUPLEX_HALF)
> +			if_mode |= ENETC_PCS_IF_MODE_DUPLEX_HALF;
>  
> +		phy_write(pcs, ENETC_PCS_IF_MODE, if_mode);
>  		phy_write(pcs, MII_BMCR, BMCR_RESET);
>  	}
>  }
> @@ -870,15 +868,18 @@ static void vsc9959_pcs_init_2500basex(struct phy_device *pcs,
>  				       unsigned int link_an_mode,
>  				       const struct phylink_link_state *state)
>  {
> +	u16 if_mode = ENETC_PCS_IF_MODE_SGMII_SPEED(ENETC_PCS_SPEED_2500) |
> +		      ENETC_PCS_IF_MODE_SGMII_EN;
> +
>  	if (link_an_mode == MLO_AN_INBAND) {
>  		phydev_err(pcs, "AN not supported on 3.125GHz SerDes lane\n");
>  		return;
>  	}
>  
> -	phy_write(pcs, ENETC_PCS_IF_MODE,
> -		  ENETC_PCS_IF_MODE_SGMII_EN |
> -		  ENETC_PCS_IF_MODE_SGMII_SPEED(ENETC_PCS_SPEED_2500));
> +	if (state->duplex == DUPLEX_HALF)
> +		if_mode |= ENETC_PCS_IF_MODE_DUPLEX_HALF;
>  
> +	phy_write(pcs, ENETC_PCS_IF_MODE, if_mode);
>  	phy_write(pcs, MII_BMCR, BMCR_RESET);
>  }
>  
> @@ -919,8 +920,11 @@ static void vsc9959_pcs_init(struct ocelot *ocelot, int port,
>  	linkmode_set_bit_array(phy_basic_ports_array,
>  			       ARRAY_SIZE(phy_basic_ports_array),
>  			       pcs->supported);
> +	linkmode_set_bit(ETHTOOL_LINK_MODE_10baseT_Half_BIT, pcs->supported);
>  	linkmode_set_bit(ETHTOOL_LINK_MODE_10baseT_Full_BIT, pcs->supported);
> +	linkmode_set_bit(ETHTOOL_LINK_MODE_100baseT_Half_BIT, pcs->supported);
>  	linkmode_set_bit(ETHTOOL_LINK_MODE_100baseT_Full_BIT, pcs->supported);
> +	linkmode_set_bit(ETHTOOL_LINK_MODE_1000baseT_Half_BIT, pcs->supported);
>  	linkmode_set_bit(ETHTOOL_LINK_MODE_1000baseT_Full_BIT, pcs->supported);
>  	if (pcs->interface == PHY_INTERFACE_MODE_2500BASEX ||
>  	    pcs->interface == PHY_INTERFACE_MODE_USXGMII)
> diff --git a/include/linux/fsl/enetc_mdio.h b/include/linux/fsl/enetc_mdio.h
> index 4875dd38af7e..2d9203314865 100644
> --- a/include/linux/fsl/enetc_mdio.h
> +++ b/include/linux/fsl/enetc_mdio.h
> @@ -15,6 +15,7 @@
>  #define ENETC_PCS_IF_MODE_SGMII_EN		BIT(0)
>  #define ENETC_PCS_IF_MODE_USE_SGMII_AN		BIT(1)
>  #define ENETC_PCS_IF_MODE_SGMII_SPEED(x)	(((x) << 2) & GENMASK(3, 2))
> +#define ENETC_PCS_IF_MODE_DUPLEX_HALF		BIT(3)
>  
>  /* Not a mistake, the SerDes PLL needs to be set at 3.125 GHz by Reset
>   * Configuration Word (RCW, outside Linux control) for 2.5G SGMII mode. The PCS
> -- 
> 2.25.1
> 
> 

-- 
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