[RFC 1/2] USB: OTG: Hold wakeupsource when VBUS present

[RFC 1/2] USB: OTG: Hold wakeupsource when VBUS present

[Kiran Kumar Raparthy]

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From: Todd Poynor <toddpoynor@google.com>

USB: OTG: Hold wakeupsource when VBUS present

Enabled by default, can disable with:
   echo N > /sys/module/otg_wakeupsource/parameters/enabled

This is one of the number of patches from the Android AOSP common.git tree,
which is used on almost all Android devices. so I wanted to submit it for
review to see if it should go upstream.

Cc: Felipe Balbi <balbi@ti.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-kernel@vger.kernel.org
Cc: linux-usb@vger.kernel.org
Cc: Android Kernel Team <kernel-team@android.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Arve Hjønnevåg <arve@android.com>
Cc: Benoit Goby <benoit@android.com>
Signed-off-by: Todd Poynor <toddpoynor@google.com>
Signed-off-by: Kiran Raparthy <kiran.kumar@linaro.org>
[kiran: Added context to commit message
	Included build fix from Benoit Goby and Arve Arve Hjønnevåg
	Removed lock->held field in driver as this mechanism is provided in wakeup.c
	wakelock(wl) terminology replaced with wakeup_source(ws)
	sys entry(module param) field modified to otg_wakeupsource
	__pm_stay_awake and __pm_relax called directly from the main
	code instead of calling them via otgws_grab,otgws_drop]
---
 drivers/usb/phy/Kconfig            |   8 ++
 drivers/usb/phy/Makefile           |   1 +
 drivers/usb/phy/otg-wakeupsource.c | 171 +++++++++++++++++++++++++++++++++++++
 3 files changed, 180 insertions(+)
 create mode 100644 drivers/usb/phy/otg-wakeupsource.c

diff --git a/drivers/usb/phy/Kconfig b/drivers/usb/phy/Kconfig
index e253fa0..9c747b2 100644
--- a/drivers/usb/phy/Kconfig
+++ b/drivers/usb/phy/Kconfig
@@ -6,6 +6,14 @@ menu "USB Physical Layer drivers"
 config USB_PHY
 	def_bool n
 
+config USB_OTG_WAKEUPSOURCE
+	bool "Hold a wakeupsource when USB connected"
+	depends on PM_SLEEP
+	select USB_PHY
+	help
+	  Select this to automatically hold a wakeupsource when USB is
+	  connected, preventing suspend.
+
 #
 # USB Transceiver Drivers
 #
diff --git a/drivers/usb/phy/Makefile b/drivers/usb/phy/Makefile
index 24a9133..ca2fbaf 100644
--- a/drivers/usb/phy/Makefile
+++ b/drivers/usb/phy/Makefile
@@ -3,6 +3,7 @@
 #
 obj-$(CONFIG_USB_PHY)			+= phy.o
 obj-$(CONFIG_OF)			+= of.o
+obj-$(CONFIG_USB_OTG_WAKEUPSOURCE)		+= otg-wakeupsource.o
 
 # transceiver drivers, keep the list sorted
 
diff --git a/drivers/usb/phy/otg-wakeupsource.c b/drivers/usb/phy/otg-wakeupsource.c
new file mode 100644
index 0000000..fa44e11
--- /dev/null
+++ b/drivers/usb/phy/otg-wakeupsource.c
@@ -0,0 +1,171 @@
+/*
+ * otg-wakeupsource.c
+ *
+ * Copyright (C) 2011 Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/notifier.h>
+#include <linux/pm_wakeup.h>
+#include <linux/spinlock.h>
+#include <linux/usb/otg.h>
+
+static bool enabled = true;
+static struct usb_phy *otgws_xceiv;
+static struct notifier_block otgws_nb;
+
+
+static DEFINE_SPINLOCK(otgws_spinlock);
+
+/*
+ * Only one lock, but since these 2 fields are associated with each other...
+ */
+
+struct otgws_lock {
+	char name[40];
+	struct wakeup_source wsource;
+};
+
+/*
+ * VBUS present lock.
+ */
+
+static struct otgws_lock vbus_lock;
+
+static int otgws_otg_notifications(struct notifier_block *nb,
+				   unsigned long event, void *unused)
+{
+	unsigned long irqflags;
+
+	if (!enabled)
+		return NOTIFY_OK;
+
+	spin_lock_irqsave(&otgws_spinlock, irqflags);
+
+	switch (event) {
+	case USB_EVENT_VBUS:
+	case USB_EVENT_ENUMERATED:
+		__pm_stay_awake(&vbus_lock.wsource);
+		break;
+
+	case USB_EVENT_NONE:
+	case USB_EVENT_ID:
+	case USB_EVENT_CHARGER:
+		__pm_relax(&vbus_lock.wsource);
+		break;
+
+	default:
+		break;
+	}
+
+	spin_unlock_irqrestore(&otgws_spinlock, irqflags);
+	return NOTIFY_OK;
+}
+
+static void sync_with_xceiv_state(void)
+{
+	if ((otgws_xceiv->last_event == USB_EVENT_VBUS) ||
+	    (otgws_xceiv->last_event == USB_EVENT_ENUMERATED))
+		__pm_stay_awake(&vbus_lock.wsource);
+	else
+		__pm_relax(&vbus_lock.wsource);
+}
+
+static int init_for_xceiv(void)
+{
+	int rv;
+	struct usb_phy *phy;
+
+	if (!otgws_xceiv) {
+		phy = usb_get_phy(USB_PHY_TYPE_USB2);
+
+		if (IS_ERR(phy)) {
+			pr_err("%s: No USB transceiver found\n", __func__);
+			return PTR_ERR(phy);
+		}
+		otgws_xceiv = phy;
+
+		snprintf(vbus_lock.name, sizeof(vbus_lock.name), "vbus-%s",
+			 dev_name(otgws_xceiv->dev));
+		wakeup_source_init(&vbus_lock.wsource, vbus_lock.name);
+
+		rv = usb_register_notifier(otgws_xceiv, &otgws_nb);
+
+		if (rv) {
+			pr_err("%s: usb_register_notifier on transceiver %s
+				failed\n", __func__,
+			       dev_name(otgws_xceiv->dev));
+			otgws_xceiv = NULL;
+			wakeup_source_trash(&vbus_lock.wsource);
+			return rv;
+		}
+	}
+
+	return 0;
+}
+
+static int set_enabled(const char *val, const struct kernel_param *kp)
+{
+	unsigned long irqflags;
+	int rv = param_set_bool(val, kp);
+
+	if (rv)
+		return rv;
+
+	rv = init_for_xceiv();
+
+	if (rv)
+		return rv;
+
+	spin_lock_irqsave(&otgws_spinlock, irqflags);
+
+	if (enabled)
+		sync_with_xceiv_state();
+	else
+		__pm_relax(&vbus_lock.wsource);
+
+	spin_unlock_irqrestore(&otgws_spinlock, irqflags);
+	return 0;
+}
+
+static struct kernel_param_ops enabled_param_ops = {
+	.set = set_enabled,
+	.get = param_get_bool,
+};
+
+module_param_cb(enabled, &enabled_param_ops, &enabled, 0644);
+MODULE_PARM_DESC(enabled, "Hold wakeupsource when VBUS present");
+
+static int __init otg_wakeupsource_init(void)
+{
+	unsigned long irqflags;
+
+	otgws_nb.notifier_call = otgws_otg_notifications;
+
+	if (!init_for_xceiv()) {
+		spin_lock_irqsave(&otgws_spinlock, irqflags);
+
+		if (enabled)
+			sync_with_xceiv_state();
+
+		spin_unlock_irqrestore(&otgws_spinlock, irqflags);
+	} else {
+		enabled = false;
+	}
+
+	return 0;
+}
+
+late_initcall(otg_wakeupsource_init);
-- 
1.8.2.1

Re: [RFC 1/2] USB: OTG: Hold wakeupsource when VBUS present

[Alan Stern]

On Fri, 22 Aug 2014, Kiran Kumar Raparthy wrote:

> From: Todd Poynor <toddpoynor@google.com>
> 
> USB: OTG: Hold wakeupsource when VBUS present
> 
> Enabled by default, can disable with:
>    echo N > /sys/module/otg_wakeupsource/parameters/enabled
> 
> This is one of the number of patches from the Android AOSP common.git tree,
> which is used on almost all Android devices. so I wanted to submit it for
> review to see if it should go upstream.

> --- a/drivers/usb/phy/Kconfig
> +++ b/drivers/usb/phy/Kconfig
> @@ -6,6 +6,14 @@ menu "USB Physical Layer drivers"
>  config USB_PHY
>  	def_bool n
>  
> +config USB_OTG_WAKEUPSOURCE
> +	bool "Hold a wakeupsource when USB connected"
> +	depends on PM_SLEEP
> +	select USB_PHY
> +	help
> +	  Select this to automatically hold a wakeupsource when USB is
> +	  connected, preventing suspend.

Without commenting on the appropriateness of this change, I'd like to
point out that users will not understand either the Kconfig symbol name
or the help text.  The help text, especially, ought to be clear even to
people not very familiar with USB.  Something more like this would be a
lot better:

	Prevent the system from going into automatic suspend while
	it is attached as a USB peripheral.

Alan Stern

Re: [RFC 1/2] USB: OTG: Hold wakeupsource when VBUS present

[Felipe Balbi]

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Hi,

On Fri, Aug 22, 2014 at 03:19:32PM +0530, Kiran Kumar Raparthy wrote:
> From: Todd Poynor <toddpoynor@google.com>
> 
> USB: OTG: Hold wakeupsource when VBUS present
> 
> Enabled by default, can disable with:

I would turn this around and make it disabled by default so that it
doesn't change behavior for distro kernels.

>    echo N > /sys/module/otg_wakeupsource/parameters/enabled
> 
> This is one of the number of patches from the Android AOSP common.git tree,
> which is used on almost all Android devices. so I wanted to submit it for
> review to see if it should go upstream.

you never explain why this is needed and you have also added some
information to commit log which shouldn't be here.

> Cc: Felipe Balbi <balbi@ti.com>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: linux-kernel@vger.kernel.org
> Cc: linux-usb@vger.kernel.org
> Cc: Android Kernel Team <kernel-team@android.com>
> Cc: John Stultz <john.stultz@linaro.org>
> Cc: Arve Hj�nnev�g <arve@android.com>
> Cc: Benoit Goby <benoit@android.com>
> Signed-off-by: Todd Poynor <toddpoynor@google.com>
> Signed-off-by: Kiran Raparthy <kiran.kumar@linaro.org>
> [kiran: Added context to commit message
> 	Included build fix from Benoit Goby and Arve Arve Hj�nnev�g
> 	Removed lock->held field in driver as this mechanism is provided in wakeup.c
> 	wakelock(wl) terminology replaced with wakeup_source(ws)
> 	sys entry(module param) field modified to otg_wakeupsource
> 	__pm_stay_awake and __pm_relax called directly from the main
> 	code instead of calling them via otgws_grab,otgws_drop]
> ---
>  drivers/usb/phy/Kconfig            |   8 ++
>  drivers/usb/phy/Makefile           |   1 +
>  drivers/usb/phy/otg-wakeupsource.c | 171 +++++++++++++++++++++++++++++++++++++
>  3 files changed, 180 insertions(+)
>  create mode 100644 drivers/usb/phy/otg-wakeupsource.c
> 
> diff --git a/drivers/usb/phy/Kconfig b/drivers/usb/phy/Kconfig
> index e253fa0..9c747b2 100644
> --- a/drivers/usb/phy/Kconfig
> +++ b/drivers/usb/phy/Kconfig
> @@ -6,6 +6,14 @@ menu "USB Physical Layer drivers"
>  config USB_PHY
>  	def_bool n
>  
> +config USB_OTG_WAKEUPSOURCE
> +	bool "Hold a wakeupsource when USB connected"
> +	depends on PM_SLEEP
> +	select USB_PHY
> +	help
> +	  Select this to automatically hold a wakeupsource when USB is
> +	  connected, preventing suspend.
> +
>  #
>  # USB Transceiver Drivers
>  #
> diff --git a/drivers/usb/phy/Makefile b/drivers/usb/phy/Makefile
> index 24a9133..ca2fbaf 100644
> --- a/drivers/usb/phy/Makefile
> +++ b/drivers/usb/phy/Makefile
> @@ -3,6 +3,7 @@
>  #
>  obj-$(CONFIG_USB_PHY)			+= phy.o
>  obj-$(CONFIG_OF)			+= of.o
> +obj-$(CONFIG_USB_OTG_WAKEUPSOURCE)		+= otg-wakeupsource.o
>  
>  # transceiver drivers, keep the list sorted
>  
> diff --git a/drivers/usb/phy/otg-wakeupsource.c b/drivers/usb/phy/otg-wakeupsource.c
> new file mode 100644
> index 0000000..fa44e11
> --- /dev/null
> +++ b/drivers/usb/phy/otg-wakeupsource.c
> @@ -0,0 +1,171 @@
> +/*
> + * otg-wakeupsource.c
> + *
> + * Copyright (C) 2011 Google, Inc.
> + *
> + * This software is licensed under the terms of the GNU General Public
> + * License version 2, as published by the Free Software Foundation, and
> + * may be copied, distributed, and modified under those terms.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/device.h>
> +#include <linux/module.h>
> +#include <linux/notifier.h>
> +#include <linux/pm_wakeup.h>
> +#include <linux/spinlock.h>
> +#include <linux/usb/otg.h>
> +
> +static bool enabled = true;
> +static struct usb_phy *otgws_xceiv;
> +static struct notifier_block otgws_nb;

this aches to be a per-PHY thing rather forcing it to be a one-for-all.

We have systems with more than one port and the PHY framework is also
starting to be used by the host side stack.

> +static DEFINE_SPINLOCK(otgws_spinlock);
> +
> +/*
> + * Only one lock, but since these 2 fields are associated with each other...
> + */

one line comment

> +
> +struct otgws_lock {
> +	char name[40];
> +	struct wakeup_source wsource;
> +};
> +
> +/*
> + * VBUS present lock.
> + */

one line comment

> +static struct otgws_lock vbus_lock;

should be per-PHY

-- 
balbi

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Re: [RFC 1/2] USB: OTG: Hold wakeupsource when VBUS present

[Todd Poynor]

On Fri, Aug 22, 2014 at 10:12 AM, Felipe Balbi <balbi@ti.com> wrote:
...
> you never explain why this is needed and you have also added some
> information to commit log which shouldn't be here.

Android uses this to prevent suspend from interfering with USB
peripheral traffic, notably adb.

The wakeup source is held only when USB is connected and enumerated
for a host session (I might be using wrong terminology here).  It may
not be necessary on a platform that implements wakeup on incoming USB
traffic, although it is likely adb and other protocols would need to
hold wakeup sources at certain times.

...
>> +static struct otgws_lock vbus_lock;
>
> should be per-PHY

One of the reasons this was done as a separate driver and via
notifiers was to keep the (original Android wakelock) logic out of the
USB code.  If the general idea is something that finds favor with the
USB and PM folks then perhaps adding a wakeup source per PHY in the
PHY driver would be better.


Todd

Re: [RFC 1/2] USB: OTG: Hold wakeupsource when VBUS present

[Felipe Balbi]

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Hi,

On Wed, Aug 27, 2014 at 02:58:30PM -0700, Todd Poynor wrote:
> On Fri, Aug 22, 2014 at 10:12 AM, Felipe Balbi <balbi@ti.com> wrote:
> ...
> > you never explain why this is needed and you have also added some
> > information to commit log which shouldn't be here.
> 
> Android uses this to prevent suspend from interfering with USB
> peripheral traffic, notably adb.

aaaaah, that's because Android freezes userspace right ?

> The wakeup source is held only when USB is connected and enumerated
> for a host session (I might be using wrong terminology here).  It may
> not be necessary on a platform that implements wakeup on incoming USB
> traffic, although it is likely adb and other protocols would need to
> hold wakeup sources at certain times.
> 
> ...
> >> +static struct otgws_lock vbus_lock;
> >
> > should be per-PHY
> 
> One of the reasons this was done as a separate driver and via
> notifiers was to keep the (original Android wakelock) logic out of the
> USB code.  If the general idea is something that finds favor with the
> USB and PM folks then perhaps adding a wakeup source per PHY in the
> PHY driver would be better.

it's best to do it per-PHY, but it doesn't have to be written into each
and every PHY driver, do it at the core and abstract that away from PHY
drivers.

-- 
balbi

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Re: [RFC 1/2] USB: OTG: Hold wakeupsource when VBUS present

[Peter Chen]

On Fri, Aug 22, 2014 at 03:19:32PM +0530, Kiran Kumar Raparthy wrote:
> From: Todd Poynor <toddpoynor@google.com>
> 
> USB: OTG: Hold wakeupsource when VBUS present
> 

It is not related to OTG, would you change a name?

> Enabled by default, can disable with:
>    echo N > /sys/module/otg_wakeupsource/parameters/enabled
> 
> This is one of the number of patches from the Android AOSP common.git tree,
> which is used on almost all Android devices. so I wanted to submit it for
> review to see if it should go upstream.
> 
> Cc: Felipe Balbi <balbi@ti.com>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: linux-kernel@vger.kernel.org
> Cc: linux-usb@vger.kernel.org
> Cc: Android Kernel Team <kernel-team@android.com>
> Cc: John Stultz <john.stultz@linaro.org>
> Cc: Arve Hj�nnev�g <arve@android.com>
> Cc: Benoit Goby <benoit@android.com>
> Signed-off-by: Todd Poynor <toddpoynor@google.com>
> Signed-off-by: Kiran Raparthy <kiran.kumar@linaro.org>
> [kiran: Added context to commit message
> 	Included build fix from Benoit Goby and Arve Arve Hj�nnev�g
> 	Removed lock->held field in driver as this mechanism is provided in wakeup.c
> 	wakelock(wl) terminology replaced with wakeup_source(ws)
> 	sys entry(module param) field modified to otg_wakeupsource
> 	__pm_stay_awake and __pm_relax called directly from the main
> 	code instead of calling them via otgws_grab,otgws_drop]
> ---
>  drivers/usb/phy/Kconfig            |   8 ++
>  drivers/usb/phy/Makefile           |   1 +
>  drivers/usb/phy/otg-wakeupsource.c | 171 +++++++++++++++++++++++++++++++++++++
>  3 files changed, 180 insertions(+)
>  create mode 100644 drivers/usb/phy/otg-wakeupsource.c
> 
> diff --git a/drivers/usb/phy/Kconfig b/drivers/usb/phy/Kconfig
> index e253fa0..9c747b2 100644
> --- a/drivers/usb/phy/Kconfig
> +++ b/drivers/usb/phy/Kconfig
> @@ -6,6 +6,14 @@ menu "USB Physical Layer drivers"
>  config USB_PHY
>  	def_bool n
>  
> +config USB_OTG_WAKEUPSOURCE
> +	bool "Hold a wakeupsource when USB connected"
> +	depends on PM_SLEEP
> +	select USB_PHY
> +	help
> +	  Select this to automatically hold a wakeupsource when USB is
> +	  connected, preventing suspend.
> +

I think it is a common driver, the UDC drivers are its best user, we
may only want to prevent the system entering suspend after UDC get
enumerated, not only just vbus is present, the PHY driver should not know
the UDC get enumerated or not, the state of enumeration belongs to
chapter 9 at USB 2.0 spec.

Peter
 
>  #
>  # USB Transceiver Drivers
>  #
> diff --git a/drivers/usb/phy/Makefile b/drivers/usb/phy/Makefile
> index 24a9133..ca2fbaf 100644
> --- a/drivers/usb/phy/Makefile
> +++ b/drivers/usb/phy/Makefile
> @@ -3,6 +3,7 @@
>  #
>  obj-$(CONFIG_USB_PHY)			+= phy.o
>  obj-$(CONFIG_OF)			+= of.o
> +obj-$(CONFIG_USB_OTG_WAKEUPSOURCE)		+= otg-wakeupsource.o
>  
>  # transceiver drivers, keep the list sorted
>  
> diff --git a/drivers/usb/phy/otg-wakeupsource.c b/drivers/usb/phy/otg-wakeupsource.c
> new file mode 100644
> index 0000000..fa44e11
> --- /dev/null
> +++ b/drivers/usb/phy/otg-wakeupsource.c
> @@ -0,0 +1,171 @@
> +/*
> + * otg-wakeupsource.c
> + *
> + * Copyright (C) 2011 Google, Inc.
> + *
> + * This software is licensed under the terms of the GNU General Public
> + * License version 2, as published by the Free Software Foundation, and
> + * may be copied, distributed, and modified under those terms.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/device.h>
> +#include <linux/module.h>
> +#include <linux/notifier.h>
> +#include <linux/pm_wakeup.h>
> +#include <linux/spinlock.h>
> +#include <linux/usb/otg.h>
> +
> +static bool enabled = true;
> +static struct usb_phy *otgws_xceiv;
> +static struct notifier_block otgws_nb;
> +
> +
> +static DEFINE_SPINLOCK(otgws_spinlock);
> +
> +/*
> + * Only one lock, but since these 2 fields are associated with each other...
> + */
> +
> +struct otgws_lock {
> +	char name[40];
> +	struct wakeup_source wsource;
> +};
> +
> +/*
> + * VBUS present lock.
> + */
> +
> +static struct otgws_lock vbus_lock;
> +
> +static int otgws_otg_notifications(struct notifier_block *nb,
> +				   unsigned long event, void *unused)
> +{
> +	unsigned long irqflags;
> +
> +	if (!enabled)
> +		return NOTIFY_OK;
> +
> +	spin_lock_irqsave(&otgws_spinlock, irqflags);
> +
> +	switch (event) {
> +	case USB_EVENT_VBUS:
> +	case USB_EVENT_ENUMERATED:
> +		__pm_stay_awake(&vbus_lock.wsource);
> +		break;
> +
> +	case USB_EVENT_NONE:
> +	case USB_EVENT_ID:
> +	case USB_EVENT_CHARGER:
> +		__pm_relax(&vbus_lock.wsource);
> +		break;
> +
> +	default:
> +		break;
> +	}
> +
> +	spin_unlock_irqrestore(&otgws_spinlock, irqflags);
> +	return NOTIFY_OK;
> +}
> +
> +static void sync_with_xceiv_state(void)
> +{
> +	if ((otgws_xceiv->last_event == USB_EVENT_VBUS) ||
> +	    (otgws_xceiv->last_event == USB_EVENT_ENUMERATED))
> +		__pm_stay_awake(&vbus_lock.wsource);
> +	else
> +		__pm_relax(&vbus_lock.wsource);
> +}
> +
> +static int init_for_xceiv(void)
> +{
> +	int rv;
> +	struct usb_phy *phy;
> +
> +	if (!otgws_xceiv) {
> +		phy = usb_get_phy(USB_PHY_TYPE_USB2);
> +
> +		if (IS_ERR(phy)) {
> +			pr_err("%s: No USB transceiver found\n", __func__);
> +			return PTR_ERR(phy);
> +		}
> +		otgws_xceiv = phy;
> +
> +		snprintf(vbus_lock.name, sizeof(vbus_lock.name), "vbus-%s",
> +			 dev_name(otgws_xceiv->dev));
> +		wakeup_source_init(&vbus_lock.wsource, vbus_lock.name);
> +
> +		rv = usb_register_notifier(otgws_xceiv, &otgws_nb);
> +
> +		if (rv) {
> +			pr_err("%s: usb_register_notifier on transceiver %s
> +				failed\n", __func__,
> +			       dev_name(otgws_xceiv->dev));
> +			otgws_xceiv = NULL;
> +			wakeup_source_trash(&vbus_lock.wsource);
> +			return rv;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static int set_enabled(const char *val, const struct kernel_param *kp)
> +{
> +	unsigned long irqflags;
> +	int rv = param_set_bool(val, kp);
> +
> +	if (rv)
> +		return rv;
> +
> +	rv = init_for_xceiv();
> +
> +	if (rv)
> +		return rv;
> +
> +	spin_lock_irqsave(&otgws_spinlock, irqflags);
> +
> +	if (enabled)
> +		sync_with_xceiv_state();
> +	else
> +		__pm_relax(&vbus_lock.wsource);
> +
> +	spin_unlock_irqrestore(&otgws_spinlock, irqflags);
> +	return 0;
> +}
> +
> +static struct kernel_param_ops enabled_param_ops = {
> +	.set = set_enabled,
> +	.get = param_get_bool,
> +};
> +
> +module_param_cb(enabled, &enabled_param_ops, &enabled, 0644);
> +MODULE_PARM_DESC(enabled, "Hold wakeupsource when VBUS present");
> +
> +static int __init otg_wakeupsource_init(void)
> +{
> +	unsigned long irqflags;
> +
> +	otgws_nb.notifier_call = otgws_otg_notifications;
> +
> +	if (!init_for_xceiv()) {
> +		spin_lock_irqsave(&otgws_spinlock, irqflags);
> +
> +		if (enabled)
> +			sync_with_xceiv_state();
> +
> +		spin_unlock_irqrestore(&otgws_spinlock, irqflags);
> +	} else {
> +		enabled = false;
> +	}
> +
> +	return 0;
> +}
> +
> +late_initcall(otg_wakeupsource_init);
> -- 
> 1.8.2.1
> 
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-- 
Best Regards,
Peter Chen

Re: [RFC 1/2] USB: OTG: Hold wakeupsource when VBUS present

[Todd Poynor]

On Fri, Aug 29, 2014 at 1:50 PM, Felipe Balbi <balbi@ti.com> wrote:
> Hi,
>
> On Wed, Aug 27, 2014 at 02:58:30PM -0700, Todd Poynor wrote:
>> On Fri, Aug 22, 2014 at 10:12 AM, Felipe Balbi <balbi@ti.com> wrote:
>> ...
>> > you never explain why this is needed and you have also added some
>> > information to commit log which shouldn't be here.
>>
>> Android uses this to prevent suspend from interfering with USB
>> peripheral traffic, notably adb.
>
> aaaaah, that's because Android freezes userspace right ?

Yes, and only wakeup interrupts will be enabled; it is a suspend-to-RAM.


Todd