Date:	Mon, 8 Sep 2014 08:38:56 -0500
From:	Felipe Balbi <balbi@...com>
To:	Kiran Kumar Raparthy <kiran.kumar@...aro.org>
CC:	<linux-kernel@...r.kernel.org>,
	Todd Poynor <toddpoynor@...gle.com>,
	Felipe Balbi <balbi@...com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.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 Hj�nnev�g <arve@...roid.com>,
	Benoit Goby <benoit@...roid.com>
Subject: Re: [RFC v3 1/2] usb: phy: Hold wakeupsource when USB is enumerated
 in peripheral mode

Hi,

On Mon, Sep 08, 2014 at 03:39:23PM +0530, Kiran Kumar Raparthy wrote:
> From: Todd Poynor <toddpoynor@...gle.com>
> 
> usb: phy: Hold wakeupsource when USB is enumerated in peripheral mode
> 
> Purpose of this is to prevent the system to enter into suspend state from USB
> peripheral traffic by hodling a wakeupsource when USB is connected and
> enumerated in peripheral mode(say adb).
> 
> Disabled by default, can enable with:
>    echo Y > /sys/module/otg_wakeupsource/parameters/enabled
> 
> 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 Hj�nnev�g <arve@...roid.com>
> Cc: Benoit Goby <benoit@...roid.com>
> Signed-off-by: Todd Poynor <toddpoynor@...gle.com>
> [kiran: Added context to commit message, squished build fixes
> from Benoit Goby and Arve Hj�nnev�g, changed wakelocks usage
> to wakeupsource, merged Todd's refactoring logic and simplified
> the structures and code and addressed community feedback]
> Signed-off-by: Kiran Raparthy <kiran.kumar@...aro.org>
> ---
> v3:
> * As per the feedback,no global phy pointer used.
> * called the one-liner wakeupsource handling calls
>   directly instead of indirect functions implemented in v2.
> * Removed indirect function get_phy_hook and used usb_get_phy
>   to get the phy handle..
> 
> v2:
> * wakeupsource handling implemeted per-PHY
> * Implemented wakeupsource handling calls in phy
> * included Todd's refactoring logic.
> 
> v1:
> * changed to "disabled by default" from "enable by default".
> * Kconfig help text modified
> * Included better commit text
> * otgws_nb moved to otg_wakeupsource_init function
> * Introduced get_phy_hook to handle otgws_xceiv per-PHY
> 
> RFC:
> * Included build fix from Benoit Goby and Arve Hj�nnev�g
> * Removed lock->held field in driver as this mechanism is
>   provided in wakeupsource driver.
> * wakelock(wl) terminology replaced with wakeup_source(ws).
> 
>  drivers/usb/phy/Kconfig            |   8 +++
>  drivers/usb/phy/Makefile           |   1 +
>  drivers/usb/phy/otg-wakeupsource.c | 136 +++++++++++++++++++++++++++++++++++++
>  include/linux/usb/phy.h            |   4 ++
>  4 files changed, 149 insertions(+)
>  create mode 100644 drivers/usb/phy/otg-wakeupsource.c
> 
> diff --git a/drivers/usb/phy/Kconfig b/drivers/usb/phy/Kconfig
> index e253fa0..d9ddd85 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 wakeupsource when USB is enumerated in peripheral mode"
> +	depends on PM_SLEEP
> +	select USB_PHY
> +	help
> +	  Prevent the system going into automatic suspend while
> +	  it is attached as a USB peripheral by holding a wakeupsource.
> +
>  #
>  # 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..d9a1720
> --- /dev/null
> +++ b/drivers/usb/phy/otg-wakeupsource.c
> @@ -0,0 +1,136 @@
> +/*
> + * 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>
> +
> +bool enabled = false;
> +
> +static DEFINE_SPINLOCK(otgws_spinlock);

why do you continue to ignore my comment that this should be built
*into* struct usb_phy so it's a per-PHY setting ? Is this some sort of a
joke that I'm not getting ?

> +static void otgws_handle_event(struct usb_phy *otgws_xceiv, unsigned long event)
> +{
> +	unsigned long irqflags;
> +
> +	spin_lock_irqsave(&otgws_spinlock, irqflags);
> +
> +	if (!enabled) {
> +		__pm_relax(&otgws_xceiv->wsource);
> +		spin_unlock_irqrestore(&otgws_spinlock, irqflags);
> +		return;
> +	}
> +
> +	switch (event) {
> +	case USB_EVENT_VBUS:
> +	case USB_EVENT_ENUMERATED:
> +		__pm_stay_awake(&otgws_xceiv->wsource);
> +		break;
> +
> +	case USB_EVENT_NONE:
> +	case USB_EVENT_ID:
> +	case USB_EVENT_CHARGER:
> +		__pm_relax(&otgws_xceiv->wsource);
> +		break;
> +
> +	default:
> +		break;
> +	}
> +
> +	spin_unlock_irqrestore(&otgws_spinlock, irqflags);
> +}
> +
> +static int otgws_otg_notifications(struct notifier_block *nb,
> +				unsigned long event, void *unused)
> +{
> +	static struct usb_phy *otgws_xceiv;
> +
> +	otgws_xceiv = usb_get_phy(USB_PHY_TYPE_USB2);
> +
> +	if (IS_ERR(otgws_xceiv)) {
> +		pr_err("%s: No OTG transceiver found\n", __func__);
> +		return PTR_ERR(otgws_xceiv);
> +	}
> +
> +	otgws_handle_event(otgws_xceiv, event);
> +
> +	return NOTIFY_OK;
> +}
> +
> +static int set_enabled(const char *val, const struct kernel_param *kp)
> +{
> +	int rv = param_set_bool(val, kp);
> +	static struct usb_phy *otgws_xceiv;
> +
> +	if (rv)
> +		return rv;
> +
> +	otgws_xceiv = usb_get_phy(USB_PHY_TYPE_USB2);
> +
> +	if (IS_ERR(otgws_xceiv)) {
> +		pr_err("%s: No OTG transceiver found\n", __func__);
> +		return PTR_ERR(otgws_xceiv);
> +	}
> +
> +	otgws_handle_event(otgws_xceiv, otgws_xceiv->last_event);
> +
> +	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");

should *not* be a kernel parameter.

> +static int __init otg_wakeupsource_init(void)

no __init

> +{
> +	int ret;
> +	char wsource_name[40];
> +	static struct usb_phy *otgws_xceiv;
> +
> +	otgws_xceiv = usb_get_phy(USB_PHY_TYPE_USB2);
> +
> +	if (IS_ERR(otgws_xceiv)) {
> +		pr_err("%s: No OTG transceiver found\n", __func__);
> +		return PTR_ERR(otgws_xceiv);
> +	}
> +
> +	snprintf(wsource_name, sizeof(wsource_name), "vbus-%s",
> +		dev_name(otgws_xceiv->dev));
> +	wakeup_source_init(&otgws_xceiv->wsource, wsource_name);
> +
> +	otgws_xceiv->otgws_nb.notifier_call = otgws_otg_notifications;
> +	ret = usb_register_notifier(otgws_xceiv, &otgws_xceiv->otgws_nb);
> +
> +	if (ret) {
> +		pr_err("%s: usb_register_notifier on transceiver %s failed\n",
> +			 __func__, dev_name(otgws_xceiv->dev));
> +		wakeup_source_trash(&otgws_xceiv->wsource);
> +		otgws_xceiv = NULL;
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +late_initcall(otg_wakeupsource_init);
> diff --git a/include/linux/usb/phy.h b/include/linux/usb/phy.h
> index 353053a..c71cf15 100644
> --- a/include/linux/usb/phy.h
> +++ b/include/linux/usb/phy.h
> @@ -88,6 +88,10 @@ struct usb_phy {
>  
>  	/* for notification of usb_phy_events */
>  	struct atomic_notifier_head	notifier;
> +	struct notifier_block	otgws_nb;
> +
> +	/* wakeup source */
> +	struct wakeup_source	wsource;
>  
>  	/* to pass extra port status to the root hub */
>  	u16			port_status;
> -- 
> 1.8.2.1
> 

-- 
balbi

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