Subject: Re: [PATCH net-next v3 2/5] net: pcs: xpcs: combine C37 SGMII AN and 2500BASEX for Intel mGbE controller

From: "Russell King (Oracle)" <[email-masked]>
Date: Thu, 21 Sep 2023 14:06:55 +0100

On Thu, Sep 21, 2023 at 08:19:43PM +0800, Choong Yong Liang wrote:
> From: "Tan, Tee Min" <[email-masked]>
> 
> This commit introduces xpcs_sgmii_2500basex_features[] that combine
> xpcs_sgmii_features[] and xpcs_2500basex_features[] for Intel mGbE
> controller that desire to interchange the speed mode of
> 10/100/1000/2500Mbps at runtime.
> 
> Also, we introduce xpcs_config_aneg_c37_sgmii_2500basex() function

Clause 37... SGMII? 2500base-X? Technically, clause 37 doesn't cover
2500base-X.

> which is called by the xpcs_do_config() with the new AN mode:
> DW_SGMII_2500BASEX, and this new function will proceed next-level
> calling to perform C37 SGMII AN/2500BASEX configuration based on
> the PHY interface updated by PHY driver.
> 
> Signed-off-by: Tan, Tee Min <[email-masked]>
> Signed-off-by: Choong Yong Liang <[email-masked]>
> ---
>  drivers/net/pcs/pcs-xpcs.c   | 72 ++++++++++++++++++++++++++++++------
>  include/linux/pcs/pcs-xpcs.h |  1 +
>  2 files changed, 62 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/net/pcs/pcs-xpcs.c b/drivers/net/pcs/pcs-xpcs.c
> index 4dbc21f604f2..60d90191677d 100644
> --- a/drivers/net/pcs/pcs-xpcs.c
> +++ b/drivers/net/pcs/pcs-xpcs.c
> @@ -104,6 +104,21 @@ static const int xpcs_2500basex_features[] = {
>  	__ETHTOOL_LINK_MODE_MASK_NBITS,
>  };
>  
> +static const int xpcs_sgmii_2500basex_features[] = {
> +	ETHTOOL_LINK_MODE_Pause_BIT,
> +	ETHTOOL_LINK_MODE_Asym_Pause_BIT,
> +	ETHTOOL_LINK_MODE_Autoneg_BIT,
> +	ETHTOOL_LINK_MODE_10baseT_Half_BIT,
> +	ETHTOOL_LINK_MODE_10baseT_Full_BIT,
> +	ETHTOOL_LINK_MODE_100baseT_Half_BIT,
> +	ETHTOOL_LINK_MODE_100baseT_Full_BIT,
> +	ETHTOOL_LINK_MODE_1000baseT_Half_BIT,
> +	ETHTOOL_LINK_MODE_1000baseT_Full_BIT,

The connected PHY could be one that supports 1000baseX as well.

> +	ETHTOOL_LINK_MODE_2500baseX_Full_BIT,
> +	ETHTOOL_LINK_MODE_2500baseT_Full_BIT,
> +	__ETHTOOL_LINK_MODE_MASK_NBITS,
> +};
> +
>  static const phy_interface_t xpcs_usxgmii_interfaces[] = {
>  	PHY_INTERFACE_MODE_USXGMII,
>  };
> @@ -133,6 +148,12 @@ static const phy_interface_t xpcs_2500basex_interfaces[] = {
>  	PHY_INTERFACE_MODE_MAX,
>  };
>  
> +static const phy_interface_t xpcs_sgmii_2500basex_interfaces[] = {
> +	PHY_INTERFACE_MODE_SGMII,
> +	PHY_INTERFACE_MODE_2500BASEX,
> +	PHY_INTERFACE_MODE_MAX,
> +};
> +
>  enum {
>  	DW_XPCS_USXGMII,
>  	DW_XPCS_10GKR,
> @@ -141,6 +162,7 @@ enum {
>  	DW_XPCS_SGMII,
>  	DW_XPCS_1000BASEX,
>  	DW_XPCS_2500BASEX,
> +	DW_XPCS_SGMII_2500BASEX,
>  	DW_XPCS_INTERFACE_MAX,
>  };
>  
> @@ -290,6 +312,7 @@ static int xpcs_soft_reset(struct dw_xpcs *xpcs,
>  	case DW_AN_C37_SGMII:
>  	case DW_2500BASEX:
>  	case DW_AN_C37_1000BASEX:
> +	case DW_SGMII_2500BASEX:
>  		dev = MDIO_MMD_VEND2;
>  		break;
>  	default:
> @@ -748,6 +771,8 @@ static int xpcs_config_aneg_c37_sgmii(struct dw_xpcs *xpcs,
>  	if (xpcs->dev_flag == DW_DEV_TXGBE)
>  		ret |= DW_VR_MII_DIG_CTRL1_PHY_MODE_CTRL;
>  
> +	/* Disable 2.5G GMII for SGMII C37 mode */
> +	ret &= ~DW_VR_MII_DIG_CTRL1_2G5_EN;

Do you know that this is correct for every user of this function?

>  	ret = xpcs_write(xpcs, MDIO_MMD_VEND2, DW_VR_MII_DIG_CTRL1, ret);
>  	if (ret < 0)
>  		return ret;
> @@ -848,6 +873,26 @@ static int xpcs_config_2500basex(struct dw_xpcs *xpcs)
>  	return xpcs_write(xpcs, MDIO_MMD_VEND2, DW_VR_MII_MMD_CTRL, ret);
>  }
>  
> +static int xpcs_config_aneg_c37_sgmii_2500basex(struct dw_xpcs *xpcs,
> +						unsigned int neg_mode,
> +						phy_interface_t interface)
> +{
> +	int ret = -EOPNOTSUPP;
> +
> +	switch (interface) {
> +	case PHY_INTERFACE_MODE_SGMII:
> +		ret = xpcs_config_aneg_c37_sgmii(xpcs, neg_mode);
> +		break;
> +	case PHY_INTERFACE_MODE_2500BASEX:
> +		ret = xpcs_config_2500basex(xpcs);
> +		break;
> +	default:
> +		break;
> +	}
> +
> +	return ret;
> +}
> +
>  int xpcs_do_config(struct dw_xpcs *xpcs, phy_interface_t interface,
>  		   const unsigned long *advertising, unsigned int neg_mode)
>  {
> @@ -890,6 +935,12 @@ int xpcs_do_config(struct dw_xpcs *xpcs, phy_interface_t interface,
>  		if (ret)
>  			return ret;
>  		break;
> +	case DW_SGMII_2500BASEX:
> +		ret = xpcs_config_aneg_c37_sgmii_2500basex(xpcs, neg_mode,
> +							   interface);
> +		if (ret)
> +			return ret;
> +		break;
>  	default:
>  		return -1;
>  	}
> @@ -1114,6 +1165,11 @@ static void xpcs_get_state(struct phylink_pcs *pcs,
>  		}
>  		break;
>  	case DW_AN_C37_SGMII:
> +	case DW_SGMII_2500BASEX:
> +		/* 2500BASEX is not supported for in-band AN mode. */
> +		if (state->interface == PHY_INTERFACE_MODE_2500BASEX)
> +			break;
> +
>  		ret = xpcs_get_state_c37_sgmii(xpcs, state);
>  		if (ret) {
>  			pr_err("xpcs_get_state_c37_sgmii returned %pe\n",
> @@ -1266,23 +1322,17 @@ static const struct xpcs_compat synopsys_xpcs_compat[DW_XPCS_INTERFACE_MAX] = {
>  		.num_interfaces = ARRAY_SIZE(xpcs_10gbaser_interfaces),
>  		.an_mode = DW_10GBASER,
>  	},
> -	[DW_XPCS_SGMII] = {
> -		.supported = xpcs_sgmii_features,
> -		.interface = xpcs_sgmii_interfaces,
> -		.num_interfaces = ARRAY_SIZE(xpcs_sgmii_interfaces),
> -		.an_mode = DW_AN_C37_SGMII,
> -	},

Doesn't this break SGMII-only support (those using DW_XPCS_SGMII) ?

>  	[DW_XPCS_1000BASEX] = {
>  		.supported = xpcs_1000basex_features,
>  		.interface = xpcs_1000basex_interfaces,
>  		.num_interfaces = ARRAY_SIZE(xpcs_1000basex_interfaces),
>  		.an_mode = DW_AN_C37_1000BASEX,
>  	},
> -	[DW_XPCS_2500BASEX] = {
> -		.supported = xpcs_2500basex_features,
> -		.interface = xpcs_2500basex_interfaces,
> -		.num_interfaces = ARRAY_SIZE(xpcs_2500basex_interfaces),
> -		.an_mode = DW_2500BASEX,

Doesn't this break 2500base-X only support (those using
DW_XPCS_2500BASEX)?

> +	[DW_XPCS_SGMII_2500BASEX] = {
> +		.supported = xpcs_sgmii_2500basex_features,
> +		.interface = xpcs_sgmii_2500basex_interfaces,
> +		.num_interfaces = ARRAY_SIZE(xpcs_sgmii_2500basex_features),
> +		.an_mode = DW_SGMII_2500BASEX,
>  	},
>  };
>  
> diff --git a/include/linux/pcs/pcs-xpcs.h b/include/linux/pcs/pcs-xpcs.h
> index da3a6c30f6d2..f075d2fca54a 100644
> --- a/include/linux/pcs/pcs-xpcs.h
> +++ b/include/linux/pcs/pcs-xpcs.h
> @@ -19,6 +19,7 @@
>  #define DW_2500BASEX			3
>  #define DW_AN_C37_1000BASEX		4
>  #define DW_10GBASER			5
> +#define DW_SGMII_2500BASEX		6
>  
>  /* device vendor OUI */
>  #define DW_OUI_WX			0x0018fc80
> -- 
> 2.25.1
> 
> 

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