usb: phy: mxs: do not set PWD.RXPWD1PT1 for low speed connection

At very rare cases, the SoF will not send out after resume with
low speed connection. The workaround is do not power down
PWD.RXPWD1PT1 bit during the suspend.
Signed-off-by: Peter Chen <peter.chen@freescale.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/phy/phy-mxs-usb.c

@@ -70,6 +70,9 @@
 #define ANADIG_USB2_LOOPBACK_SET		0x244
 #define ANADIG_USB2_LOOPBACK_CLR		0x248
 
+#define ANADIG_USB1_MISC			0x1f0
+#define ANADIG_USB2_MISC			0x250
+
 #define BM_ANADIG_ANA_MISC0_STOP_MODE_CONFIG	BIT(12)
 #define BM_ANADIG_ANA_MISC0_STOP_MODE_CONFIG_SL BIT(11)
 
@@ -81,6 +84,11 @@
 #define BM_ANADIG_USB2_LOOPBACK_UTMI_DIG_TST1	BIT(2)
 #define BM_ANADIG_USB2_LOOPBACK_TSTI_TX_EN	BIT(5)
 
+#define BM_ANADIG_USB1_MISC_RX_VPIN_FS		BIT(29)
+#define BM_ANADIG_USB1_MISC_RX_VMIN_FS		BIT(28)
+#define BM_ANADIG_USB2_MISC_RX_VPIN_FS		BIT(29)
+#define BM_ANADIG_USB2_MISC_RX_VMIN_FS		BIT(28)
+
 #define to_mxs_phy(p) container_of((p), struct mxs_phy, phy)
 
 /* Do disconnection between PHY and controller without vbus */
@@ -323,13 +331,50 @@ static void mxs_phy_shutdown(struct usb_phy *phy)
 	clk_disable_unprepare(mxs_phy->clk);
 }
 
+static bool mxs_phy_is_low_speed_connection(struct mxs_phy *mxs_phy)
+{
+	unsigned int line_state;
+	/* bit definition is the same for all controllers */
+	unsigned int dp_bit = BM_ANADIG_USB1_MISC_RX_VPIN_FS,
+		     dm_bit = BM_ANADIG_USB1_MISC_RX_VMIN_FS;
+	unsigned int reg = ANADIG_USB1_MISC;
+
+	/* If the SoCs don't have anatop, quit */
+	if (!mxs_phy->regmap_anatop)
+		return false;
+
+	if (mxs_phy->port_id == 0)
+		reg = ANADIG_USB1_MISC;
+	else if (mxs_phy->port_id == 1)
+		reg = ANADIG_USB2_MISC;
+
+	regmap_read(mxs_phy->regmap_anatop, reg, &line_state);
+
+	if ((line_state & (dp_bit | dm_bit)) ==  dm_bit)
+		return true;
+	else
+		return false;
+}
+
 static int mxs_phy_suspend(struct usb_phy *x, int suspend)
 {
 	int ret;
 	struct mxs_phy *mxs_phy = to_mxs_phy(x);
+	bool low_speed_connection, vbus_is_on;
+
+	low_speed_connection = mxs_phy_is_low_speed_connection(mxs_phy);
+	vbus_is_on = mxs_phy_get_vbus_status(mxs_phy);
 
 	if (suspend) {
-		writel(0xffffffff, x->io_priv + HW_USBPHY_PWD);
+		/*
+		 * FIXME: Do not power down RXPWD1PT1 bit for low speed
+		 * connect. The low speed connection will have problem at
+		 * very rare cases during usb suspend and resume process.
+		 */
+		if (low_speed_connection & vbus_is_on)
+			writel(0xfffbffff, x->io_priv + HW_USBPHY_PWD);
+		else
+			writel(0xffffffff, x->io_priv + HW_USBPHY_PWD);
 		writel(BM_USBPHY_CTRL_CLKGATE,
 		       x->io_priv + HW_USBPHY_CTRL_SET);
 		clk_disable_unprepare(mxs_phy->clk);