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

From: Serge Semin
Date: Tue Sep 26 2023 - 06:52:10 EST

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Hi Choong

On Thu, Sep 21, 2023 at 08:19:43PM +0800, Choong Yong Liang wrote:
> From: "Tan, Tee Min" <tee.min.tan@xxxxxxxxxxxxxxx>
>
> 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
> 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.

Why do you even need all of those changes? Please thoroughly justify
because ... (see below)

>
> Signed-off-by: Tan, Tee Min <tee.min.tan@xxxxxxxxxxxxxxx>
> Signed-off-by: Choong Yong Liang <yong.liang.choong@xxxxxxxxxxxxxxx>
> ---
> 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,
> + 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,
> +};
> +

... these are just a combination of the
xpcs_sgmii_features[]/xpcs_sgmii_interfaces[] and
xpcs_2500basex_features[]/xpcs_2500basex_interfaces[] data which are
already supported by the generic DW XPCS code. All of these features
and interfaces are checked in the xpcs_create() method and then get to
be combined in the framework of the xpcs_validate() and
xpcs_get_interfaces() functions. And ...

> 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;

* This is the only specific change in this patch. But it can be
* applied independently from the rest of the changes. Although I agree
* with Russel, it must be double checked since may cause regressions
* on the other platforms.

> 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;
> +}
> +

... this is just a copy of the code which is already available in xpcs_do_config():

< compat = xpcs_find_compat(xpcs->id, interface);
< if (!compat)
< return -ENODEV;
<
< switch (compat->an_mode) {
< ...
< case DW_AN_C37_SGMII:
< ret = xpcs_config_aneg_c37_sgmii(xpcs, neg_mode);
< if (ret)
< return ret;
< break;
< ...
< case DW_2500BASEX:
< ret = xpcs_config_2500basex(xpcs);
< if (ret)
< return ret;
< break;

So based on the passed interface xpcs_find_compat() will find a proper
compat descriptor, which an_mode field will be then utilized to call
the respective config method. Thus, unless I miss something, basically
you won't need any of the changes below and the most of the changes
above reducing the patch to just a few lines.

-Serge(y)

> 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,
> - },
> [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,
> + [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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