[PATCH] phy: tegra: xusb: reset VBUS & ID OVERRIDE

[Henry Lin <henryl@nvidia.com>]

From: BH Hsieh <bhsieh@nvidia.com>

Observed VBUS_OVERRIDE & ID_OVERRIDE might be programmed
with unexpected value prior to XUSB PADCTL driver, this
could also occur in virtualization scenario.

For example, UEFI firmware programs ID_OVERRIDE=GROUNDED to set
a type-c port to host mode and keeps the value to kernel.
If the type-c port is connected a usb host, below errors can be
observed right after USB host mode driver gets probed. The errors
would keep until usb role class driver detects the type-c port
as device mode and notifies usb device mode driver to set both
ID_OVERRIDE and VBUS_OVERRIDE to correct value by XUSB PADCTL
driver.

[  173.765814] usb usb3-port2: Cannot enable. Maybe the USB cable is bad?
[  173.765837] usb usb3-port2: config error

Taking virtualization into account, asserting XUSB PADCTL
reset would break XUSB functions used by other guest OS,
hence only reset VBUS & ID OVERRIDE of the port in
utmi_phy_init.

Fixes: bbf711682cd5 ("phy: tegra: xusb: Add Tegra186 support")
Cc: stable@vger.kernel.org
Signed-off-by: BH Hsieh <bhsieh@nvidia.com>
Signed-off-by: Henry Lin <henryl@nvidia.com>
---
 drivers/phy/tegra/xusb-tegra186.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/phy/tegra/xusb-tegra186.c b/drivers/phy/tegra/xusb-tegra186.c
index 0f60d5d1c167..34c6d424a3e8 100644
--- a/drivers/phy/tegra/xusb-tegra186.c
+++ b/drivers/phy/tegra/xusb-tegra186.c
@@ -928,6 +928,7 @@ static int tegra186_utmi_phy_init(struct phy *phy)
 	unsigned int index = lane->index;
 	struct device *dev = padctl->dev;
 	int err;
+	u32 reg;
 
 	port = tegra_xusb_find_usb2_port(padctl, index);
 	if (!port) {
@@ -935,6 +936,13 @@ static int tegra186_utmi_phy_init(struct phy *phy)
 		return -ENODEV;
 	}
 
+	/* reset VBUS&ID OVERRIDE */
+	reg = padctl_readl(padctl, USB2_VBUS_ID);
+	reg &= ~VBUS_OVERRIDE;
+	reg &= ~ID_OVERRIDE(~0);
+	reg |= ID_OVERRIDE_FLOATING;
+	padctl_writel(padctl, reg, USB2_VBUS_ID);
+
 	if (port->supply && port->mode == USB_DR_MODE_HOST) {
 		err = regulator_enable(port->supply);
 		if (err) {
-- 
2.25.1