phy: rockchip: naneng-combphy: Fix PCIe L1ss support RK3528

When PCIe link enters L1 PM substates, the PHY will turn off its
PLL for power-saving. However, it turns off the PLL too fast which
leads the PHY to be broken. According to the PHY document, we need
to delay PLL turnoff time.

Fixes: bbcca4f ("phy: rockchip: naneng-combphy: Add RK3528 support")
Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patch.msgid.link/1763459526-35004-1-git-send-email-shawn.lin@rock-chips.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

Author: shawn1221

drivers/phy/rockchip/phy-rockchip-naneng-combphy.c

@@ -21,6 +21,9 @@
 #define REF_CLOCK_100MHz		(100 * HZ_PER_MHZ)
 
 /* RK3528 COMBO PHY REG */
+#define RK3528_PHYREG5				0x14
+#define RK3528_PHYREG5_GATE_TX_PCK_SEL		BIT(3)
+#define RK3528_PHYREG5_GATE_TX_PCK_DLY_PLL_OFF	BIT(3)
 #define RK3528_PHYREG6				0x18
 #define RK3528_PHYREG6_PLL_KVCO			GENMASK(12, 10)
 #define RK3528_PHYREG6_PLL_KVCO_VALUE		0x2
@@ -504,6 +507,10 @@ static int rk3528_combphy_cfg(struct rockchip_combphy_priv *priv)
 	case REF_CLOCK_100MHz:
 		rockchip_combphy_param_write(priv->phy_grf, &cfg->pipe_clk_100m, true);
 		if (priv->type == PHY_TYPE_PCIE) {
+			/* Gate_tx_pck_sel length select for L1ss support */
+			rockchip_combphy_updatel(priv, RK3528_PHYREG5_GATE_TX_PCK_SEL,
+						 RK3528_PHYREG5_GATE_TX_PCK_DLY_PLL_OFF, RK3528_PHYREG5);
+
 			/* PLL KVCO tuning fine */
 			val = FIELD_PREP(RK3528_PHYREG6_PLL_KVCO, RK3528_PHYREG6_PLL_KVCO_VALUE);
 			rockchip_combphy_updatel(priv, RK3528_PHYREG6_PLL_KVCO, val,