[PATCH 2/5] phy: tegra: xusb: Fix USB2 port regulator disable logic

Diogo Ivo
2025-12-04T21:37:18Z

The USB2 PHY mode handling on Tegra210 incorrectly relied on
regulator_is_enabled() when determining whether the VBUS supply should
be disabled during role changes. This is because regulator_is_enabled()
reports exactly what is states and not if there is an unbalanced number
of calls between regulator_enable() and regulator_disable(). For
example, regulator_is_enabled() always reports true on a fixed-regulator
with no enable gpio, which is the case on the Pixel C.

This then leads to the PHY driver wrongfully calling regulator_disable()
when transitioning from USB_ROLE_DEVICE to USB_ROLE_NONE since the driver
did not previously call the corresponding regulator_enable().

Fix this by keeping track of the current role and updating the logic to
disable the regulator only when the previous role was USB_ROLE_HOST.

While at it fix a small typo in a comment.

Signed-off-by: Diogo Ivo <diogo.ivo@tecnico.ulisboa.pt>
---
drivers/phy/tegra/xusb-tegra210.c | 5 +++--
drivers/phy/tegra/xusb.h | 1 +
2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/phy/tegra/xusb-tegra210.c b/drivers/phy/tegra/xusb-tegra210.c
index 3409924498e9..63ad57d95514 100644
--- a/drivers/phy/tegra/xusb-tegra210.c
+++ b/drivers/phy/tegra/xusb-tegra210.c
@@ -1934,9 +1934,9 @@ static int tegra210_usb2_phy_set_mode(struct phy *phy, enum phy_mode mode,
/*
* When port is peripheral only or role transitions to
* USB_ROLE_NONE from USB_ROLE_DEVICE, regulator is not
- * be enabled.
+ * enabled.
*/
- if (regulator_is_enabled(port->supply))
+ if (port->role == USB_ROLE_HOST)
regulator_disable(port->supply);

tegra210_xusb_padctl_id_override(padctl, false);
@@ -1944,6 +1944,7 @@ static int tegra210_usb2_phy_set_mode(struct phy *phy, enum phy_mode mode,
}
}

+ port->role = submode;
mutex_unlock(&padctl->lock);

return err;
diff --git a/drivers/phy/tegra/xusb.h b/drivers/phy/tegra/xusb.h
index d2b5f9565132..273af147dfd3 100644
--- a/drivers/phy/tegra/xusb.h
+++ b/drivers/phy/tegra/xusb.h
@@ -317,6 +317,7 @@ struct tegra_xusb_usb2_port {
enum usb_dr_mode mode;
bool internal;
int usb3_port_fake;
+ enum usb_role role;
};

static inline struct tegra_xusb_usb2_port *

--
2.52.0