[RFC PATCH 3/8] net: pcs: pcs-mtk-lynxi: use 2500Base-X without AN

[Daniel Golle <daniel@makrotopia.org>]

Using 2500Base-T SFP modules e.g. on the BananaPi R3 requires manually
disabling auto-negotiation, e.g. using ethtool. While a proper fix
using SFP quirks is being discussed upstream, bring a work-around to
restore user experience to what it was before the switch to the
dedicated SGMII PCS driver.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>
---
 drivers/net/pcs/pcs-mtk-lynxi.c | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/drivers/net/pcs/pcs-mtk-lynxi.c b/drivers/net/pcs/pcs-mtk-lynxi.c
index 8501dd365279b..6204448d8eac6 100644
--- a/drivers/net/pcs/pcs-mtk-lynxi.c
+++ b/drivers/net/pcs/pcs-mtk-lynxi.c
@@ -92,14 +92,23 @@ static void mtk_pcs_lynxi_get_state(struct phylink_pcs *pcs,
 				    struct phylink_link_state *state)
 {
 	struct mtk_pcs_lynxi *mpcs = pcs_to_mtk_pcs_lynxi(pcs);
-	unsigned int bm, adv;
+	unsigned int bm, bmsr, adv;
 
 	/* Read the BMSR and LPA */
 	regmap_read(mpcs->regmap, SGMSYS_PCS_CONTROL_1, &bm);
-	regmap_read(mpcs->regmap, SGMSYS_PCS_ADVERTISE, &adv);
+	bmsr = FIELD_GET(SGMII_BMSR, bm);
+
+	if (state->interface == PHY_INTERFACE_MODE_2500BASEX) {
+		state->link = !!(bmsr & BMSR_LSTATUS);
+		state->an_complete = !!(bmsr & BMSR_ANEGCOMPLETE);
+		state->speed = SPEED_2500;
+		state->duplex = DUPLEX_FULL;
+
+		return;
+	}
 
-	phylink_mii_c22_pcs_decode_state(state, FIELD_GET(SGMII_BMSR, bm),
-					 FIELD_GET(SGMII_LPA, adv));
+	regmap_read(mpcs->regmap, SGMSYS_PCS_ADVERTISE, &adv);
+	phylink_mii_c22_pcs_decode_state(state, bmsr, FIELD_GET(SGMII_LPA, adv));
 }
 
 static int mtk_pcs_lynxi_config(struct phylink_pcs *pcs, unsigned int neg_mode,
@@ -129,7 +138,8 @@ static int mtk_pcs_lynxi_config(struct phylink_pcs *pcs, unsigned int neg_mode,
 	if (neg_mode & PHYLINK_PCS_NEG_INBAND)
 		sgm_mode |= SGMII_REMOTE_FAULT_DIS;
 
-	if (neg_mode == PHYLINK_PCS_NEG_INBAND_ENABLED) {
+	if (neg_mode == PHYLINK_PCS_NEG_INBAND_ENABLED &&
+	    interface != PHY_INTERFACE_MODE_2500BASEX) {
 		if (interface == PHY_INTERFACE_MODE_SGMII)
 			sgm_mode |= SGMII_SPEED_DUPLEX_AN;
 		bmcr = BMCR_ANENABLE;
-- 
2.42.1