Re: [RFC/PATCH 1/2] usb: gadget: let gadgets control pullup on their own

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On Wed, 6 Feb 2013, Felipe Balbi wrote:

> This is useful on gadgets that depend on userland
> daemons to function properly. We can delay connection
> to the host until userland is ready.

> --- a/drivers/usb/gadget/udc-core.c
> +++ b/drivers/usb/gadget/udc-core.c
> @@ -235,7 +235,18 @@ static void usb_gadget_remove_driver(struct usb_udc *udc)
>  
>  	kobject_uevent(&udc->dev.kobj, KOBJ_CHANGE);
>  
> -	usb_gadget_disconnect(udc->gadget);
> +	/*
> +	 * NOTICE: if gadget driver wants to control
> +	 * pullup, it needs to make sure that when
> +	 * user tries to rmmod the gadget driver, it
> +	 * will disconnect the pullups before returning
> +	 * from its ->unbind() method.
> +	 *
> +	 * We are truly trusting the gadget driver here.
> +	 */
> +	if (!udc->driver->controls_pullups)
> +		usb_gadget_disconnect(udc->gadget);

Even though you trust the gadget driver about when to enable the 
pullup, doesn't it make sense to disable the pullup whenever the gadget 
driver is removed, regardless?

Alan Stern

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