usb: chipidea: imx: improve logic if samsung,picophy-* parameter is 0

In current driver, the value of tuning parameter will not take effect
if samsung,picophy-* is assigned as 0. Because 0 is also a valid value
acccording to the description of USB_PHY_CFG1 register, this will improve
the logic to let it work.

Fixes: 58a3cefb ("usb: chipidea: imx: add two samsung picophy parameters tuning implementation")
cc: <stable@vger.kernel.org>
Signed-off-by: Xu Yang <xu.yang_2@nxp.com>
Acked-by: Peter Chen <peter.chen@kernel.org>
Link: https://lore.kernel.org/r/20230627112126.1882666-1-xu.yang_2@nxp.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/chipidea/ci_hdrc_imx.c

@@ -176,10 +176,12 @@ static struct imx_usbmisc_data *usbmisc_get_init_data(struct device *dev)
 	if (of_usb_get_phy_mode(np) == USBPHY_INTERFACE_MODE_ULPI)
 		data->ulpi = 1;
 
-	of_property_read_u32(np, "samsung,picophy-pre-emp-curr-control",
-			&data->emp_curr_control);
-	of_property_read_u32(np, "samsung,picophy-dc-vol-level-adjust",
-			&data->dc_vol_level_adjust);
+	if (of_property_read_u32(np, "samsung,picophy-pre-emp-curr-control",
+			&data->emp_curr_control))
+		data->emp_curr_control = -1;
+	if (of_property_read_u32(np, "samsung,picophy-dc-vol-level-adjust",
+			&data->dc_vol_level_adjust))
+		data->dc_vol_level_adjust = -1;
 
 	return data;
 }

drivers/usb/chipidea/usbmisc_imx.c

@@ -660,13 +660,15 @@ static int usbmisc_imx7d_init(struct imx_usbmisc_data *data)
 			usbmisc->base + MX7D_USBNC_USB_CTRL2);
 		/* PHY tuning for signal quality */
 		reg = readl(usbmisc->base + MX7D_USB_OTG_PHY_CFG1);
-		if (data->emp_curr_control && data->emp_curr_control <=
+		if (data->emp_curr_control >= 0 &&
+			data->emp_curr_control <=
 			(TXPREEMPAMPTUNE0_MASK >> TXPREEMPAMPTUNE0_BIT)) {
 			reg &= ~TXPREEMPAMPTUNE0_MASK;
 			reg |= (data->emp_curr_control << TXPREEMPAMPTUNE0_BIT);
 		}
 
-		if (data->dc_vol_level_adjust && data->dc_vol_level_adjust <=
+		if (data->dc_vol_level_adjust >= 0 &&
+			data->dc_vol_level_adjust <=
 			(TXVREFTUNE0_MASK >> TXVREFTUNE0_BIT)) {
 			reg &= ~TXVREFTUNE0_MASK;
 			reg |= (data->dc_vol_level_adjust << TXVREFTUNE0_BIT);