From df202d996d72665c76d031849aa064c4881dc777 Mon Sep 17 00:00:00 2001
From: Samuel Holland <samuel@sholland.org>
Date: Thu, 14 Jul 2022 22:34:53 -0500
Subject: [PATCH] phy: sun4i-usb: Do not drive VBUS with external VBUS present

It is possible to use host-side USB with externally-provided VBUS. For
example, some USB OTG cables have an extra power input which powers
both the board and the USB peripheral.

To support this setup, skip enabling the VBUS switch/regulator if VBUS
voltage is already present. This behavior matches the Linux PHY driver.

Signed-off-by: Samuel Holland <samuel@sholland.org>
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
 drivers/phy/allwinner/phy-sun4i-usb.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/phy/allwinner/phy-sun4i-usb.c b/drivers/phy/allwinner/phy-sun4i-usb.c
index 2e969ab91e..6428163c18 100644
--- a/drivers/phy/allwinner/phy-sun4i-usb.c
+++ b/drivers/phy/allwinner/phy-sun4i-usb.c
@@ -224,6 +224,12 @@ static int sun4i_usb_phy_power_on(struct phy *phy)
 		initial_usb_scan_delay = 0;
 	}
 
+	/* For phy0 only turn on Vbus if we don't have an ext. Vbus */
+	if (phy->id == 0 && sun4i_usb_phy_vbus_detect(phy)) {
+		dev_warn(phy->dev, "External vbus detected, not enabling our own vbus\n");
+		return 0;
+	}
+
 	if (dm_gpio_is_valid(&usb_phy->gpio_vbus))
 		dm_gpio_set_value(&usb_phy->gpio_vbus, 1);
 
-- 
2.39.5