phy: tegra: xusb: Fix unbalanced regulator disable in UTMI PHY mode

When transitioning from USB_ROLE_DEVICE to USB_ROLE_NONE, the code
assumed that the regulator should be disabled. However, if the regulator
is marked as always-on, regulator_is_enabled() continues to return true,
leading to an incorrect attempt to disable a regulator which is not
enabled.

This can result in warnings such as:

[  250.155624] WARNING: CPU: 1 PID: 7326 at drivers/regulator/core.c:3004
_regulator_disable+0xe4/0x1a0
[  250.155652] unbalanced disables for VIN_SYS_5V0

To fix this, we move the regulator control logic into
tegra186_xusb_padctl_id_override() function since it's directly related
to the ID override state. The regulator is now only disabled when the role
transitions from USB_ROLE_HOST to USB_ROLE_NONE, by checking the VBUS_ID
register. This ensures that regulator enable/disable operations are
properly balanced and only occur when actually transitioning to/from host
mode.

Fixes: 49d46e3c7e59 ("phy: tegra: xusb: Add set_mode support for UTMI phy on Tegra186")
Cc: stable@vger.kernel.org
Signed-off-by: Wayne Chang <waynec@nvidia.com>
Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Link: https://lore.kernel.org/r/20250502092606.2275682-1-waynec@nvidia.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

diff --git a/drivers/phy/tegra/xusb-tegra186.c b/drivers/phy/tegra/xusb-tegra186.c
index ba668c77457f1b1af45194d48316faea8338ee93..e818f6c3980e6b9028567db09404b31e5a839b5d 100644 (file)
--- a/drivers/phy/tegra/xusb-tegra186.c
+++ b/drivers/phy/tegra/xusb-tegra186.c
@@ -783,13 +783,15 @@ static int tegra186_xusb_padctl_vbus_override(struct tegra_xusb_padctl *padctl,
 }
 
 static int tegra186_xusb_padctl_id_override(struct tegra_xusb_padctl *padctl,
-                                           bool status)
+                                           struct tegra_xusb_usb2_port *port, bool status)
 {
-       u32 value;
+       u32 value, id_override;
+       int err = 0;
 
        dev_dbg(padctl->dev, "%s id override\n", status ? "set" : "clear");
 
        value = padctl_readl(padctl, USB2_VBUS_ID);
+       id_override = value & ID_OVERRIDE(~0);
 
        if (status) {
                if (value & VBUS_OVERRIDE) {
@@ -800,15 +802,35 @@ static int tegra186_xusb_padctl_id_override(struct tegra_xusb_padctl *padctl,
                        value = padctl_readl(padctl, USB2_VBUS_ID);
                }
 
-               value &= ~ID_OVERRIDE(~0);
-               value |= ID_OVERRIDE_GROUNDED;
+               if (id_override != ID_OVERRIDE_GROUNDED) {
+                       value &= ~ID_OVERRIDE(~0);
+                       value |= ID_OVERRIDE_GROUNDED;
+                       padctl_writel(padctl, value, USB2_VBUS_ID);
+
+                       err = regulator_enable(port->supply);
+                       if (err) {
+                               dev_err(padctl->dev, "Failed to enable regulator: %d\n", err);
+                               return err;
+                       }
+               }
        } else {
-               value &= ~ID_OVERRIDE(~0);
-               value |= ID_OVERRIDE_FLOATING;
+               if (id_override == ID_OVERRIDE_GROUNDED) {
+                       /*
+                        * The regulator is disabled only when the role transitions
+                        * from USB_ROLE_HOST to USB_ROLE_NONE.
+                        */
+                       err = regulator_disable(port->supply);
+                       if (err) {
+                               dev_err(padctl->dev, "Failed to disable regulator: %d\n", err);
+                               return err;
+                       }
+
+                       value &= ~ID_OVERRIDE(~0);
+                       value |= ID_OVERRIDE_FLOATING;
+                       padctl_writel(padctl, value, USB2_VBUS_ID);
+               }
        }
 
-       padctl_writel(padctl, value, USB2_VBUS_ID);
-
        return 0;
 }
 
@@ -827,27 +849,20 @@ static int tegra186_utmi_phy_set_mode(struct phy *phy, enum phy_mode mode,
 
        if (mode == PHY_MODE_USB_OTG) {
                if (submode == USB_ROLE_HOST) {
-                       tegra186_xusb_padctl_id_override(padctl, true);
-
-                       err = regulator_enable(port->supply);
+                       err = tegra186_xusb_padctl_id_override(padctl, port, true);
+                       if (err)
+                               goto out;
                } else if (submode == USB_ROLE_DEVICE) {
                        tegra186_xusb_padctl_vbus_override(padctl, true);
                } else if (submode == USB_ROLE_NONE) {
-                       /*
-                        * When port is peripheral only or role transitions to
-                        * USB_ROLE_NONE from USB_ROLE_DEVICE, regulator is not
-                        * enabled.
-                        */
-                       if (regulator_is_enabled(port->supply))
-                               regulator_disable(port->supply);
-
-                       tegra186_xusb_padctl_id_override(padctl, false);
+                       err = tegra186_xusb_padctl_id_override(padctl, port, false);
+                       if (err)
+                               goto out;
                        tegra186_xusb_padctl_vbus_override(padctl, false);
                }
        }
-
+out:
        mutex_unlock(&padctl->lock);
-
        return err;
 }