linux-kernel - RE: [PATCH v3 3/3] usb: phy: hold wakeupsource when USB is enumerated in peripheral mode

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Date:	Tue, 25 Nov 2014 07:06:18 +0000
From:	Peter Chen <Peter.Chen@...escale.com>
To:	Kiran Raparthy <kiran.kumar@...aro.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Felipe Balbi <balbi@...com>
CC:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	Android Kernel Team <kernel-team@...roid.com>,
	John Stultz <john.stultz@...aro.org>,
	Sumit Semwal <sumit.semwal@...aro.org>,
	Arve Hjønnevåg <arve@...roid.com>,
	Benoit Goby <benoit@...roid.com>,
	Todd Poynor <toddpoynor@...gle.com>
Subject: RE: [PATCH v3 3/3] usb: phy: hold wakeupsource when USB is enumerated
 in peripheral mode

 
> 
> usb: phy: hold wakeupsource when USB is enumerated in peripheral mode
> 
> Some systems require a mechanism to prevent system to enter into suspend
> state when USB is connected and enumerated in peripheral mode.
> 
> This patch provides an interface to hold a wakeupsource to prevent suspend.
> PHY drivers can use this interface when USB is connected and enumerated in
> peripheral mode.
> 
> A timed wakeupsource is temporarily held on USB disconnect events, to allow
> the rest of the system to react to the USB disconnection (dropping host
> sessions, updating charger status, etc.) prior to re-allowing suspend.
> 

Hi Kiran & Felipe,

Just two questions for this series

- Will it be the default behavior for all peripheral drivers?
- If the peripheral driver's PHY driver does not vbus event, how to support it?
For example, chipidea udc driver has its vbus interface at its controller register.

Peter

> Cc: Felipe Balbi <balbi@...com>
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Cc: linux-kernel@...r.kernel.org
> Cc: linux-usb@...r.kernel.org
> Cc: Android Kernel Team <kernel-team@...roid.com>
> Cc: John Stultz <john.stultz@...aro.org>
> Cc: Sumit Semwal <sumit.semwal@...aro.org>
> Cc: Arve Hjønnevåg <arve@...roid.com>
> Cc: Benoit Goby <benoit@...roid.com>
> [Original patch in Android from Todd]
> Cc: Todd Poynor <toddpoynor@...gle.com>
> Signed-off-by: Kiran Raparthy <kiran.kumar@...aro.org>
> ---
>  drivers/usb/phy/phy.c   | 29 +++++++++++++++++++++++++++--
>  include/linux/usb/phy.h |  5 +++++
>  2 files changed, 32 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/usb/phy/phy.c b/drivers/usb/phy/phy.c index
> b4066a0..8c87bc3 100644
> --- a/drivers/usb/phy/phy.c
> +++ b/drivers/usb/phy/phy.c
> @@ -331,6 +331,7 @@ int usb_add_phy(struct usb_phy *x, enum
> usb_phy_type type)
>  	int		ret = 0;
>  	unsigned long	flags;
>  	struct usb_phy	*phy;
> +	char wsource_name[40];
> 
>  	if (x->type != USB_PHY_TYPE_UNDEFINED) {
>  		dev_err(x->dev, "not accepting initialized PHY %s\n", x->label);
> @@ -353,6 +354,10 @@ int usb_add_phy(struct usb_phy *x, enum
> usb_phy_type type)
>  	x->type = type;
>  	list_add_tail(&x->head, &phy_list);
> 
> +	snprintf(wsource_name, sizeof(wsource_name), "vbus-%s",
> +		dev_name(x->dev));
> +	wakeup_source_init(&x->wsource, wsource_name);
> +
>  out:
>  	spin_unlock_irqrestore(&phy_lock, flags);
>  	return ret;
> @@ -404,6 +409,7 @@ void usb_remove_phy(struct usb_phy *x)
> 
>  	spin_lock_irqsave(&phy_lock, flags);
>  	if (x) {
> +		wakeup_source_trash(&x->wsource);
>  		list_for_each_entry(phy_bind, &phy_bind_list, list)
>  			if (phy_bind->phy == x)
>  				phy_bind->phy = NULL;
> @@ -448,13 +454,32 @@ int usb_bind_phy(const char *dev_name, u8 index,
> EXPORT_SYMBOL_GPL(usb_bind_phy);
> 
>  /**
> - * usb_phy_set_event - set event to phy event
> + * usb_phy_set_event - set event to phy event and
> + * hold/temporarily hold wakeupsource
>   * @x: the phy returned by usb_get_phy();
>   *
> - * This sets event to phy event
> + * This holds per-PHY wakeupsource/timed wakeupsource
>   */
>  void usb_phy_set_event(struct usb_phy *x, unsigned long event)  {
> +
>  	x->last_event = event;
> +
> +	switch (event) {
> +	case USB_EVENT_ENUMERATED:
> +		__pm_stay_awake(&x->wsource);
> +		break;
> +
> +	case USB_EVENT_NONE:
> +	case USB_EVENT_ID:
> +	case USB_EVENT_VBUS:
> +	case USB_EVENT_CHARGER:
> +		__pm_wakeup_event(&x->wsource,
> +				  USB_PHY_DEFAULT_WAKEUP_SRC_TIMEOUT);
> +		break;
> +
> +	default:
> +		break;
> +	}
>  }
>  EXPORT_SYMBOL_GPL(usb_phy_set_event);
> diff --git a/include/linux/usb/phy.h b/include/linux/usb/phy.h index
> f499c23..63a56bf 100644
> --- a/include/linux/usb/phy.h
> +++ b/include/linux/usb/phy.h
> @@ -12,6 +12,8 @@
>  #include <linux/notifier.h>
>  #include <linux/usb.h>
> 
> +#define USB_PHY_DEFAULT_WAKEUP_SRC_TIMEOUT
> 	msecs_to_jiffies(2000)
> +
>  enum usb_phy_interface {
>  	USBPHY_INTERFACE_MODE_UNKNOWN,
>  	USBPHY_INTERFACE_MODE_UTMI,
> @@ -88,6 +90,9 @@ struct usb_phy {
>  	/* for notification of usb_phy_events */
>  	struct atomic_notifier_head	notifier;
> 
> +	/* wakeup source */
> +	struct wakeup_source    wsource;
> +
>  	/* to pass extra port status to the root hub */
>  	u16			port_status;
>  	u16			port_change;
> --
> 1.9.1
> 
> --
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