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    Subject[PATCH AUTOSEL 5.4 181/350] phy: qcom-usb-hs: Fix extcon double register after power cycle
    Date
    From: Stephan Gerhold <stephan@gerhold.net>

    [ Upstream commit 64f86b9978449ff05bfa6c64b4c5439e21e9c80b ]

    Commit f0b5c2c96370 ("phy: qcom-usb-hs: Replace the extcon API")
    switched from extcon_register_notifier() to the resource-managed
    API, i.e. devm_extcon_register_notifier().

    This is problematic in this case, because the extcon notifier
    is dynamically registered/unregistered whenever the PHY is powered
    on/off. The resource-managed API does not unregister the notifier
    until the driver is removed, so as soon as the PHY is power cycled,
    attempting to register the notifier again results in:

    double register detected
    WARNING: CPU: 1 PID: 182 at kernel/notifier.c:26 notifier_chain_register+0x74/0xa0
    Call trace:
    ...
    extcon_register_notifier+0x74/0xb8
    devm_extcon_register_notifier+0x54/0xb8
    qcom_usb_hs_phy_power_on+0x1fc/0x208
    ...

    ... and USB stops working after plugging the cable out and in
    another time.

    The easiest way to fix this is to make a partial revert of
    commit f0b5c2c96370 ("phy: qcom-usb-hs: Replace the extcon API")
    and avoid using the resource-managed API in this case.

    Fixes: f0b5c2c96370 ("phy: qcom-usb-hs: Replace the extcon API")
    Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
    Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/phy/qualcomm/phy-qcom-usb-hs.c | 7 +++++--
    1 file changed, 5 insertions(+), 2 deletions(-)

    diff --git a/drivers/phy/qualcomm/phy-qcom-usb-hs.c b/drivers/phy/qualcomm/phy-qcom-usb-hs.c
    index b163b3a1558d5..61054272a7c8b 100644
    --- a/drivers/phy/qualcomm/phy-qcom-usb-hs.c
    +++ b/drivers/phy/qualcomm/phy-qcom-usb-hs.c
    @@ -158,8 +158,8 @@ static int qcom_usb_hs_phy_power_on(struct phy *phy)
    /* setup initial state */
    qcom_usb_hs_phy_vbus_notifier(&uphy->vbus_notify, state,
    uphy->vbus_edev);
    - ret = devm_extcon_register_notifier(&ulpi->dev, uphy->vbus_edev,
    - EXTCON_USB, &uphy->vbus_notify);
    + ret = extcon_register_notifier(uphy->vbus_edev, EXTCON_USB,
    + &uphy->vbus_notify);
    if (ret)
    goto err_ulpi;
    }
    @@ -180,6 +180,9 @@ static int qcom_usb_hs_phy_power_off(struct phy *phy)
    {
    struct qcom_usb_hs_phy *uphy = phy_get_drvdata(phy);

    + if (uphy->vbus_edev)
    + extcon_unregister_notifier(uphy->vbus_edev, EXTCON_USB,
    + &uphy->vbus_notify);
    regulator_disable(uphy->v3p3);
    regulator_disable(uphy->v1p8);
    clk_disable_unprepare(uphy->sleep_clk);
    --
    2.20.1
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