[PATCH RFC net-next 4/4] net: xpcs: allow 1000BASE-X to work with older XPCS IP
From: Russell King (Oracle) <hidden>
Date: 2025-02-05 13:28:14
Subsystem:
ethernet phy library, networking drivers, synopsys designware ethernet xpcs driver, the rest · Maintainers:
Andrew Lunn, Heiner Kallweit, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
Older XPCS IP requires SGMII_LINK and PHY_SIDE_SGMII to be set when operating in 1000BASE-X mode even though the XPCS is not configured for SGMII. An example of a device with older XPCS IP is KSZ9477. We already don't clear these bits if we switch from SGMII to 1000BASE-X on TXGBE - which would result in 1000BASE-X with the PHY_SIDE_SGMII bit left set. It is currently believed to be safe to set both bits on newer IP without side-effects. Signed-off-by: Russell King (Oracle) <redacted> --- drivers/net/pcs/pcs-xpcs.c | 13 +++++++++++-- drivers/net/pcs/pcs-xpcs.h | 1 + 2 files changed, 12 insertions(+), 2 deletions(-)
diff --git a/drivers/net/pcs/pcs-xpcs.c b/drivers/net/pcs/pcs-xpcs.c
index 1eba0c583f16..d522e4a5a138 100644
--- a/drivers/net/pcs/pcs-xpcs.c
+++ b/drivers/net/pcs/pcs-xpcs.c@@ -774,9 +774,18 @@ static int xpcs_config_aneg_c37_1000basex(struct dw_xpcs *xpcs, return ret; } - mask = DW_VR_MII_PCS_MODE_MASK; + /* Older XPCS IP requires PHY_MODE (bit 3) and SGMII_LINK (but 4) to + * be set when operating in 1000BASE-X mode. See page 233 + * https://ww1.microchip.com/downloads/aemDocuments/documents/OTH/ProductDocuments/DataSheets/KSZ9477S-Data-Sheet-DS00002392C.pdf + * "5.5.9 SGMII AUTO-NEGOTIATION CONTROL REGISTER" + */ + mask = DW_VR_MII_PCS_MODE_MASK | DW_VR_MII_AN_CTRL_SGMII_LINK | + DW_VR_MII_TX_CONFIG_MASK; val = FIELD_PREP(DW_VR_MII_PCS_MODE_MASK, - DW_VR_MII_PCS_MODE_C37_1000BASEX); + DW_VR_MII_PCS_MODE_C37_1000BASEX) | + FIELD_PREP(DW_VR_MII_TX_CONFIG_MASK, + DW_VR_MII_TX_CONFIG_PHY_SIDE_SGMII) | + DW_VR_MII_AN_CTRL_SGMII_LINK; if (!xpcs->pcs.poll) { mask |= DW_VR_MII_AN_INTR_EN;
diff --git a/drivers/net/pcs/pcs-xpcs.h b/drivers/net/pcs/pcs-xpcs.h
index 96117bd9e2b6..f0ddd93c7a22 100644
--- a/drivers/net/pcs/pcs-xpcs.h
+++ b/drivers/net/pcs/pcs-xpcs.h@@ -73,6 +73,7 @@ /* VR_MII_AN_CTRL */ #define DW_VR_MII_AN_CTRL_8BIT BIT(8) +#define DW_VR_MII_AN_CTRL_SGMII_LINK BIT(4) #define DW_VR_MII_TX_CONFIG_MASK BIT(3) #define DW_VR_MII_TX_CONFIG_PHY_SIDE_SGMII 0x1 #define DW_VR_MII_TX_CONFIG_MAC_SIDE_SGMII 0x0
--
2.30.2