Re: [PATCH] phy: qcom-usb-hs: Fix extcon double register after power cycle

[Chanwoo Choi <cw00.choi@samsung.com>]

On 19. 10. 8. 오후 8:52, Stephan Gerhold wrote:
> 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>
> ---
> An other way to fix this would be keep the extcon notifier
> permanently registered, and check in qcom_usb_hs_phy_vbus_notifier
> if the PHY is currently powered on.
> ---
>  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 b163b3a1558d..61054272a7c8 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);
> 

Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>

-- 
Best Regards,
Chanwoo Choi
Samsung Electronics