linux-kernel - [RFC v1 2/2] usb: otg: Temporarily hold wakeupsource on charger and disconnect events

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Message-Id: <1409219749-26911-1-git-send-email-kiran.kumar@linaro.org>
Date:	Thu, 28 Aug 2014 15:25:49 +0530
From:	Kiran Kumar Raparthy <kiran.kumar@...aro.org>
To:	linux-kernel@...r.kernel.org
Cc:	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>,
	Kiran Raparthy <kiran.kumar@...aro.org>
Subject: [RFC v1 2/2] usb: otg: Temporarily hold wakeupsource on charger and disconnect events

From: Todd Poynor <toddpoynor@...gle.com>

usb: otg: Temporarily hold wakeupsource on charger and disconnect events

Allow other parts of the system to react to the charger connect/disconnect
event without allowing the system to suspend before the other parts can process
the event. This wakeup_source times out after 2 seconds; if nobody else holds a
wakeup_source by that time then the device can sleep.

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>
Signed-off-by: Todd Poynor <toddpoynor@...gle.com>
[kiran: Added context to commit message]
Signed-off-by: Kiran Raparthy <kiran.kumar@...aro.org>
---
 drivers/usb/phy/otg-wakeupsource.c | 10 +++++++---
 include/linux/usb/otg.h            |  2 ++
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/phy/otg-wakeupsource.c b/drivers/usb/phy/otg-wakeupsource.c
index 7c838d1..9f3c5c1 100644
--- a/drivers/usb/phy/otg-wakeupsource.c
+++ b/drivers/usb/phy/otg-wakeupsource.c
@@ -34,8 +34,11 @@ struct otgws_lock {
 	struct wakeup_source wsource;
 };
 
-/* VBUS present lock */
-
+/*
+ * VBUS present lock.  Also used as a timed lock on charger
+ * connect/disconnect and USB host disconnect, to allow the system
+ * to react to the change in power.
+ */
 static struct otgws_lock vbus_lock;
 
 static void otgws_handle_event(unsigned long event)
@@ -59,7 +62,8 @@ static void otgws_handle_event(unsigned long event)
 	case USB_EVENT_NONE:
 	case USB_EVENT_ID:
 	case USB_EVENT_CHARGER:
-		__pm_relax(&vbus_lock.wsource);
+		__pm_wakeup_event(&vbus_lock.wsource,
+		msecs_to_jiffies(TEMPORARY_HOLD_TIME));
 		break;
 
 	default:
diff --git a/include/linux/usb/otg.h b/include/linux/usb/otg.h
index 154332b..4243747 100644
--- a/include/linux/usb/otg.h
+++ b/include/linux/usb/otg.h
@@ -11,6 +11,8 @@
 
 #include <linux/usb/phy.h>
 
+#define TEMPORARY_HOLD_TIME    2000
+
 struct usb_otg {
 	u8			default_a;
 
-- 
1.8.2.1

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