[PATCH] phy: rockchip: naneng-combphy: Fix TX detect RX termination errata

[Shawn Lin]

Some PHY revisions may fail to detect the peer RX's termination
resistor (RTERM) under certain critical temperature conditions.
This causes TX detection failures on PCIe links.

Add a workaround to force the RTERM detection ready signal for
affected PHY revisions. This ensures reliable TX-to-RX termination
detection across all operating temperature ranges.

The fix applies to RK3562, RK3568, RK3576 and RK3588 SoCs which share
the same PHY IP with this hardware errata.

Signed-off-by: Shawn Lin <shawn.lin at rock-chips.com>
---

 drivers/phy/rockchip/phy-rockchip-naneng-combphy.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/drivers/phy/rockchip/phy-rockchip-naneng-combphy.c b/drivers/phy/rockchip/phy-rockchip-naneng-combphy.c
index b60d6bf..76d4994 100644
--- a/drivers/phy/rockchip/phy-rockchip-naneng-combphy.c
+++ b/drivers/phy/rockchip/phy-rockchip-naneng-combphy.c
@@ -106,6 +106,9 @@
 #define RK3568_PHYREG18				0x44
 #define RK3568_PHYREG18_PLL_LOOP		0x32
 
+#define RK3568_PHYREG26				0x64
+#define RK3568_PHYREG26_FORCE_RTERM_DET_RDY	BIT(5)
+
 #define RK3568_PHYREG30				0x74
 #define RK3568_PHYREG30_GATE_TX_PCK_SEL         BIT(7)
 #define RK3568_PHYREG30_GATE_TX_PCK_DLY_PLL_OFF BIT(7)
@@ -193,6 +196,7 @@ struct rockchip_combphy_cfg {
 	unsigned int num_phys;
 	unsigned int phy_ids[3];
 	const struct rockchip_combphy_grfcfg *grfcfg;
+	bool force_rxterm_det_rdy;
 	int (*combphy_cfg)(struct rockchip_combphy_priv *priv);
 };
 
@@ -264,6 +268,17 @@ static int rockchip_combphy_init(struct phy *phy)
 
 	switch (priv->type) {
 	case PHY_TYPE_PCIE:
+		/*
+		 * Hardware Errata: TX fails to detect peer RX termination.
+		 * Some PHY revisions may fail to detect remote RX's RTERM
+		 * (receiver termination resistor) under certain critical
+		 * temperature conditions. Set force rterm detect ready to
+		 * fix it.
+		 */
+		if (priv->cfg->force_rxterm_det_rdy)
+			rockchip_combphy_updatel(priv, RK3568_PHYREG26_FORCE_RTERM_DET_RDY,
+					RK3568_PHYREG26_FORCE_RTERM_DET_RDY, RK3568_PHYREG26);
+		fallthrough;
 	case PHY_TYPE_USB3:
 	case PHY_TYPE_SATA:
 	case PHY_TYPE_SGMII:
@@ -745,6 +760,7 @@ static const struct rockchip_combphy_cfg rk3562_combphy_cfgs = {
 	},
 	.grfcfg		= &rk3562_combphy_grfcfgs,
 	.combphy_cfg	= rk3562_combphy_cfg,
+	.force_rxterm_det_rdy  = true,
 };
 
 static int rk3568_combphy_cfg(struct rockchip_combphy_priv *priv)
@@ -962,6 +978,7 @@ static const struct rockchip_combphy_cfg rk3568_combphy_cfgs = {
 	},
 	.grfcfg		= &rk3568_combphy_grfcfgs,
 	.combphy_cfg	= rk3568_combphy_cfg,
+	.force_rxterm_det_rdy  = true,
 };
 
 static int rk3576_combphy_cfg(struct rockchip_combphy_priv *priv)
@@ -1231,6 +1248,7 @@ static const struct rockchip_combphy_cfg rk3576_combphy_cfgs = {
 	},
 	.grfcfg		= &rk3576_combphy_grfcfgs,
 	.combphy_cfg	= rk3576_combphy_cfg,
+	.force_rxterm_det_rdy  = true,
 };
 
 static int rk3588_combphy_cfg(struct rockchip_combphy_priv *priv)
@@ -1418,6 +1436,7 @@ static const struct rockchip_combphy_cfg rk3588_combphy_cfgs = {
 	},
 	.grfcfg		= &rk3588_combphy_grfcfgs,
 	.combphy_cfg	= rk3588_combphy_cfg,
+	.force_rxterm_det_rdy  = true,
 };
 
 static const struct of_device_id rockchip_combphy_of_match[] = {
-- 
2.7.4