[PATCH 1/1] phy: tegra: xusb: Fix unbalanced regulator disable in UTMI PHY mode
Jon Hunter
jonathanh at nvidia.com
Thu May 15 04:03:47 PDT 2025
On 02/05/2025 10:26, Wayne Chang wrote:
> 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 at vger.kernel.org
> Signed-off-by: Wayne Chang <waynec at nvidia.com>
> ---
> drivers/phy/tegra/xusb-tegra186.c | 59 +++++++++++++++++++------------
> 1 file changed, 37 insertions(+), 22 deletions(-)
>
> diff --git a/drivers/phy/tegra/xusb-tegra186.c b/drivers/phy/tegra/xusb-tegra186.c
> index fae6242aa730..1b35d50821f7 100644
> --- a/drivers/phy/tegra/xusb-tegra186.c
> +++ b/drivers/phy/tegra/xusb-tegra186.c
> @@ -774,13 +774,15 @@ 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) {
> @@ -791,15 +793,35 @@ 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;
> }
>
> @@ -818,27 +840,20 @@ 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;
> }
>
Reviewed-by: Jon Hunter <jonathanh at nvidia.com>
Tested-by: Jon Hunter <jonathanh at nvidia.com>
Thanks for fixing this!
Jon
--
nvpublic
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