[PATCH net-next v7 2/7] net: pcs: xpcs: re-initiate clause 37 Auto-negotiation

Choong Yong Liang
2025-02-06T13:20:35Z

The xpcs_switch_interface_mode function was introduced to handle
interface switching.

According to the XPCS datasheet, a soft reset is required to initiate
Clause 37 auto-negotiation when the XPCS switches interface modes.

When the interface mode is set to 2500BASE-X, Clause 37 auto-negotiation
is turned off.

Subsequently, when the interface mode switches from 2500BASE-X to SGMII,
re-initiating Clause 37 auto-negotiation is required for the SGMII
interface mode to function properly.

Signed-off-by: Choong Yong Liang <yong.liang.choong@linux.intel.com>
---
drivers/net/pcs/pcs-xpcs-wx.c | 4 +--
drivers/net/pcs/pcs-xpcs.c | 60 ++++++++++++++++++++++++++++++++---
2 files changed, 57 insertions(+), 7 deletions(-)

diff --git a/drivers/net/pcs/pcs-xpcs-wx.c b/drivers/net/pcs/pcs-xpcs-wx.c
index fc52f7aa5f59..f73ab04d09f0 100644
--- a/drivers/net/pcs/pcs-xpcs-wx.c
+++ b/drivers/net/pcs/pcs-xpcs-wx.c
@@ -172,11 +172,9 @@ int txgbe_xpcs_switch_mode(struct dw_xpcs *xpcs, phy_interface_t interface)
return 0;
}

- if (xpcs->interface == interface && !txgbe_xpcs_mode_quirk(xpcs))
+ if (!txgbe_xpcs_mode_quirk(xpcs))
return 0;

- xpcs->interface = interface;
-
ret = txgbe_pcs_poll_power_up(xpcs);
if (ret < 0)
return ret;
diff --git a/drivers/net/pcs/pcs-xpcs.c b/drivers/net/pcs/pcs-xpcs.c
index 1faa37f0e7b9..fb3d1548a8e0 100644
--- a/drivers/net/pcs/pcs-xpcs.c
+++ b/drivers/net/pcs/pcs-xpcs.c
@@ -817,6 +817,58 @@ static int xpcs_config_2500basex(struct dw_xpcs *xpcs)
BMCR_SPEED1000);
}

+static int xpcs_switch_to_aneg_c37_sgmii(const struct dw_xpcs_compat *compat,
+ struct dw_xpcs *xpcs,
+ unsigned int neg_mode)
+{
+ bool an_c37_enabled;
+ int ret, mdio_ctrl;
+
+ if (neg_mode == PHYLINK_PCS_NEG_INBAND_ENABLED) {
+ mdio_ctrl = xpcs_read(xpcs, MDIO_MMD_VEND2, MII_BMCR);
+ if (mdio_ctrl < 0)
+ return mdio_ctrl;
+
+ an_c37_enabled = mdio_ctrl & BMCR_ANENABLE;
+ if (!an_c37_enabled) {
+ //Perform soft reset to initiate C37 auto-negotiation
+ ret = xpcs_soft_reset(xpcs, compat);
+ if (ret)
+ return ret;
+ }
+ }
+ return 0;
+}
+
+static int xpcs_switch_interface_mode(const struct dw_xpcs_compat *compat,
+ struct dw_xpcs *xpcs,
+ phy_interface_t interface,
+ unsigned int neg_mode)
+{
+ int ret = 0;
+
+ if (xpcs->interface != interface) {
+ if (xpcs->info.pma == WX_TXGBE_XPCS_PMA_10G_ID) {
+ ret = txgbe_xpcs_switch_mode(xpcs, interface);
+ } else {
+ switch (compat->an_mode) {
+ case DW_AN_C37_SGMII:
+ ret = xpcs_switch_to_aneg_c37_sgmii(compat, xpcs, neg_mode);
+ break;
+ default:
+ break;
+ }
+ }
+
+ if (ret)
+ return ret;
+
+ xpcs->interface = interface;
+ }
+
+ return 0;
+}
+
static int xpcs_do_config(struct dw_xpcs *xpcs, phy_interface_t interface,
const unsigned long *advertising,
unsigned int neg_mode)
@@ -828,11 +880,11 @@ static int xpcs_do_config(struct dw_xpcs *xpcs, phy_interface_t interface,
if (!compat)
return -ENODEV;

- if (xpcs->info.pma == WX_TXGBE_XPCS_PMA_10G_ID) {
- ret = txgbe_xpcs_switch_mode(xpcs, interface);
- if (ret)
- return ret;
+ ret = xpcs_switch_interface_mode(compat, xpcs, interface, neg_mode);
+ if (ret)
+ return ret;

+ if (xpcs->info.pma == WX_TXGBE_XPCS_PMA_10G_ID) {
/* Wangxun devices need backplane CL37 AN enabled for
* SGMII and 1000base-X
*/
--
2.34.1