Re: [RFC][PATCH 1/9] usb: hcd: Introduce usb_start/stop_hcd()

[Peter Chen <peter.chen@freescale.com>]

On Wed, Mar 18, 2015 at 03:55:55PM +0200, Roger Quadros wrote:
> To support OTG we want a mechanism to start and stop
> the HCD from the OTG state machine. Add usb_start_hcd()
> and usb_stop_hcd().

Hi Roger,

You may not need to create another pair of hcd APIs for doing
it, you can use usb_add_hcd/usb_remove_hcd directly, it is safer
and cleaner. The chipidea uses it for both ID role switch use case
and OTG FSM use case.

Peter
> 
> Signed-off-by: Roger Quadros <rogerq@ti.com>
> ---
>  drivers/usb/core/hcd.c  | 147 ++++++++++++++++++++++++++++++++----------------
>  include/linux/usb/hcd.h |   2 +
>  2 files changed, 100 insertions(+), 49 deletions(-)
> 
> diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
> index 45a915c..e28bd9d 100644
> --- a/drivers/usb/core/hcd.c
> +++ b/drivers/usb/core/hcd.c
> @@ -2613,7 +2613,76 @@ static void usb_put_invalidate_rhdev(struct usb_hcd *hcd)
>  }
>  
>  /**
> - * usb_add_hcd - finish generic HCD structure initialization and register
> + * usb_start_hcd - start the HCD
> + * @hcd: the usb_hcd structure to initialize
> + *
> + * calls the drivers start() routine, registers the root hub
> + * and creates the USB sysfs attributes.
> + */
> +int usb_start_hcd(struct usb_hcd *hcd)
> +{
> +	int retval;
> +	struct usb_device *rhdev = hcd->self.root_hub;
> +
> +	if (hcd->state != HC_STATE_HALT) {
> +		dev_err(hcd->self.controller, "not starting a running HCD\n");
> +		return -EINVAL;
> +	}
> +
> +	hcd->state = HC_STATE_RUNNING;
> +	retval = hcd->driver->start(hcd);
> +	if (retval < 0) {
> +		dev_err(hcd->self.controller, "startup error %d\n", retval);
> +		hcd->state = HC_STATE_HALT;
> +		return retval;
> +	}
> +
> +	/* starting here, usbcore will pay attention to this root hub */
> +	if ((retval = register_root_hub(hcd)) != 0)
> +		goto err_register_root_hub;
> +
> +	retval = sysfs_create_group(&rhdev->dev.kobj, &usb_bus_attr_group);
> +	if (retval < 0) {
> +		pr_err("Cannot register USB bus sysfs attributes: %d\n",
> +		       retval);
> +		goto error_create_attr_group;
> +	}
> +	if (hcd->uses_new_polling && HCD_POLL_RH(hcd))
> +		usb_hcd_poll_rh_status(hcd);
> +
> +	return retval;
> +
> +error_create_attr_group:
> +	clear_bit(HCD_FLAG_RH_RUNNING, &hcd->flags);
> +	if (HC_IS_RUNNING(hcd->state))
> +		hcd->state = HC_STATE_QUIESCING;
> +	spin_lock_irq(&hcd_root_hub_lock);
> +	hcd->rh_registered = 0;
> +	spin_unlock_irq(&hcd_root_hub_lock);
> +
> +#ifdef CONFIG_PM
> +	cancel_work_sync(&hcd->wakeup_work);
> +#endif
> +	mutex_lock(&usb_bus_list_lock);
> +	usb_disconnect(&rhdev);		/* Sets rhdev to NULL */
> +	mutex_unlock(&usb_bus_list_lock);
> +err_register_root_hub:
> +	hcd->rh_pollable = 0;
> +	clear_bit(HCD_FLAG_POLL_RH, &hcd->flags);
> +	del_timer_sync(&hcd->rh_timer);
> +	hcd->driver->stop(hcd);
> +	hcd->state = HC_STATE_HALT;
> +
> +	/* In case the HCD restarted the timer, stop it again. */
> +	clear_bit(HCD_FLAG_POLL_RH, &hcd->flags);
> +	del_timer_sync(&hcd->rh_timer);
> +
> +	return retval;
> +}
> +EXPORT_SYMBOL_GPL(usb_start_hcd);
> +
> +/**
> + * usb_add_hcd - finish generic HCD structure initialization and register.
>   * @hcd: the usb_hcd structure to initialize
>   * @irqnum: Interrupt line to allocate
>   * @irqflags: Interrupt type flags
> @@ -2757,50 +2826,12 @@ int usb_add_hcd(struct usb_hcd *hcd,
>  			goto err_request_irq;
>  	}
>  
> -	hcd->state = HC_STATE_RUNNING;
> -	retval = hcd->driver->start(hcd);
> -	if (retval < 0) {
> -		dev_err(hcd->self.controller, "startup error %d\n", retval);
> +	retval = usb_start_hcd(hcd);
> +	if (retval)
>  		goto err_hcd_driver_start;
> -	}
> -
> -	/* starting here, usbcore will pay attention to this root hub */
> -	if ((retval = register_root_hub(hcd)) != 0)
> -		goto err_register_root_hub;
> -
> -	retval = sysfs_create_group(&rhdev->dev.kobj, &usb_bus_attr_group);
> -	if (retval < 0) {
> -		printk(KERN_ERR "Cannot register USB bus sysfs attributes: %d\n",
> -		       retval);
> -		goto error_create_attr_group;
> -	}
> -	if (hcd->uses_new_polling && HCD_POLL_RH(hcd))
> -		usb_hcd_poll_rh_status(hcd);
> -
> -	return retval;
>  
> -error_create_attr_group:
> -	clear_bit(HCD_FLAG_RH_RUNNING, &hcd->flags);
> -	if (HC_IS_RUNNING(hcd->state))
> -		hcd->state = HC_STATE_QUIESCING;
> -	spin_lock_irq(&hcd_root_hub_lock);
> -	hcd->rh_registered = 0;
> -	spin_unlock_irq(&hcd_root_hub_lock);
> +	return 0;
>  
> -#ifdef CONFIG_PM
> -	cancel_work_sync(&hcd->wakeup_work);
> -#endif
> -	mutex_lock(&usb_bus_list_lock);
> -	usb_disconnect(&rhdev);		/* Sets rhdev to NULL */
> -	mutex_unlock(&usb_bus_list_lock);
> -err_register_root_hub:
> -	hcd->rh_pollable = 0;
> -	clear_bit(HCD_FLAG_POLL_RH, &hcd->flags);
> -	del_timer_sync(&hcd->rh_timer);
> -	hcd->driver->stop(hcd);
> -	hcd->state = HC_STATE_HALT;
> -	clear_bit(HCD_FLAG_POLL_RH, &hcd->flags);
> -	del_timer_sync(&hcd->rh_timer);
>  err_hcd_driver_start:
>  	if (usb_hcd_is_primary_hcd(hcd) && hcd->irq > 0)
>  		free_irq(irqnum, hcd);
> @@ -2830,18 +2861,20 @@ err_phy:
>  EXPORT_SYMBOL_GPL(usb_add_hcd);
>  
>  /**
> - * usb_remove_hcd - shutdown processing for generic HCDs
> - * @hcd: the usb_hcd structure to remove
> - * Context: !in_interrupt()
> + * usb_stop_hcd - stop the HCD
> + * @hcd: the usb_hcd structure to initialize
>   *
> - * Disconnects the root hub, then reverses the effects of usb_add_hcd(),
> - * invoking the HCD's stop() method.
> + * removes the USB sysfs attributes, disconnects the root hub
> + * and calls the driver's stop() routine.
>   */
> -void usb_remove_hcd(struct usb_hcd *hcd)
> +void usb_stop_hcd(struct usb_hcd *hcd)
>  {
>  	struct usb_device *rhdev = hcd->self.root_hub;
>  
> -	dev_info(hcd->self.controller, "remove, state %x\n", hcd->state);
> +	if (hcd->state == HC_STATE_HALT) {
> +		dev_err(hcd->self.controller, "not stopping a halted HCD\n");
> +		return;
> +	}
>  
>  	usb_get_dev(rhdev);
>  	sysfs_remove_group(&rhdev->dev.kobj, &usb_bus_attr_group);
> @@ -2888,6 +2921,22 @@ void usb_remove_hcd(struct usb_hcd *hcd)
>  	/* In case the HCD restarted the timer, stop it again. */
>  	clear_bit(HCD_FLAG_POLL_RH, &hcd->flags);
>  	del_timer_sync(&hcd->rh_timer);
> +}
> +EXPORT_SYMBOL_GPL(usb_stop_hcd);
> +
> +/**
> + * usb_remove_hcd - shutdown processing for generic HCDs
> + * @hcd: the usb_hcd structure to remove
> + * Context: !in_interrupt()
> + *
> + * Disconnects the root hub, then reverses the effects of usb_add_hcd(),
> + * invoking the HCD's stop() method.
> + */
> +void usb_remove_hcd(struct usb_hcd *hcd)
> +{
> +	dev_info(hcd->self.controller, "remove, state %x\n", hcd->state);
> +
> +	usb_stop_hcd(hcd);
>  
>  	if (usb_hcd_is_primary_hcd(hcd)) {
>  		if (hcd->irq > 0)
> diff --git a/include/linux/usb/hcd.h b/include/linux/usb/hcd.h
> index 68b1e83..12aaf4c 100644
> --- a/include/linux/usb/hcd.h
> +++ b/include/linux/usb/hcd.h
> @@ -433,6 +433,8 @@ extern void usb_put_hcd(struct usb_hcd *hcd);
>  extern int usb_hcd_is_primary_hcd(struct usb_hcd *hcd);
>  extern int usb_add_hcd(struct usb_hcd *hcd,
>  		unsigned int irqnum, unsigned long irqflags);
> +extern int usb_start_hcd(struct usb_hcd *hcd);
> +extern void usb_stop_hcd(struct usb_hcd *hcd);
>  extern void usb_remove_hcd(struct usb_hcd *hcd);
>  extern int usb_hcd_find_raw_port_number(struct usb_hcd *hcd, int port1);
>  
> -- 
> 2.1.0
> 

-- 

Best Regards,
Peter Chen