linux-kernel - [PATCH] USB: Increment wakeup count on remote wakeup.

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Message-Id: <20180419001850.133110-1-ravisadineni@chromium.org>
Date:   Wed, 18 Apr 2018 17:18:50 -0700
From:   Ravi Chandra Sadineni <ravisadineni@...omium.org>
To:     stern@...land.harvard.edu, gregkh@...uxfoundation.org,
        martin.blumenstingl@...glemail.com, ravisadineni@...gle.com,
        chunfeng.yun@...iatek.com, johan@...nel.org,
        arvind.yadav.cs@...il.com, dtor@...gle.com,
        anton.bondarenko.sama@...il.com, f.fainelli@...il.com,
        keescook@...omium.org, mathias.nyman@...ux.intel.com,
        felipe.balbi@...ux.intel.com, ekorenevsky@...il.com,
        peter.chen@....com, joe@...ches.com
Cc:     tbroch@...gle.com, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org, rajatja@...gle.com,
        bleung@...gle.com,
        Ravi Chandra Sadineni <ravisadineni@...omium.org>
Subject: [PATCH] USB: Increment wakeup count on remote wakeup.

On chromebooks we depend on wakeup count to identify the wakeup source.
But currently USB devices do not increment the wakeup count when they
trigger the remote wake. This patch addresses the same.

Resume condition is reported differently on USB 2.0 and USB 3.0 devices.

On USB 2.0 devices, a wake capable device, if wake enabled, drives
resume signal to indicate a remote wake (USB 2.0 spec section 7.1.7.7).
The upstream facing port then sets C_PORT_SUSPEND bit and reports a
port change event (USB 2.0 spec section 11.24.2.7.2.3). Thus if a port
has resumed before driving the resume signal from the host and
C_PORT_SUSPEND is set, then the device attached to the given port might
be the reason for the last system wakeup. Increment the wakeup count for
the same.

On USB 3.0 devices, a function may signal that it wants to exit from device
suspend by sending a Function Wake Device Notification to the host (USB3.0
spec section 8.5.6.4) Thus on receiving the Function Wake, increment the
wakeup count.

Signed-off-by: ravisadineni@...omium.org
---
 drivers/usb/core/hcd.c |  1 +
 drivers/usb/core/hub.c | 12 ++++++++++--
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
index 777036ae63674..79f95a878fb6e 100644
--- a/drivers/usb/core/hcd.c
+++ b/drivers/usb/core/hcd.c
@@ -2375,6 +2375,7 @@ void usb_hcd_resume_root_hub (struct usb_hcd *hcd)
 {
 	unsigned long flags;
 
+	pm_wakeup_event(dev, 0);
 	spin_lock_irqsave (&hcd_root_hub_lock, flags);
 	if (hcd->rh_registered) {
 		set_bit(HCD_FLAG_WAKEUP_PENDING, &hcd->flags);
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index f6ea16e9f6bb9..6abc5be1bcbf5 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -653,12 +653,17 @@ void usb_wakeup_notification(struct usb_device *hdev,
 		unsigned int portnum)
 {
 	struct usb_hub *hub;
+	struct usb_port *port_dev;
 
 	if (!hdev)
 		return;
 
 	hub = usb_hub_to_struct_hub(hdev);
 	if (hub) {
+		port_dev = hub->ports[portnum - 1];
+		if (port_dev && port_dev->child)
+			pm_wakeup_event(&port_dev->child->dev, 0);
+
 		set_bit(portnum, hub->wakeup_bits);
 		kick_hub_wq(hub);
 	}
@@ -3432,10 +3437,13 @@ int usb_port_resume(struct usb_device *udev, pm_message_t msg)
 
 	usb_lock_port(port_dev);
 
-	/* Skip the initial Clear-Suspend step for a remote wakeup */
 	status = hub_port_status(hub, port1, &portstatus, &portchange);
-	if (status == 0 && !port_is_suspended(hub, portstatus))
+	/* Skip the initial Clear-Suspend step for a remote wakeup */
+	if (status == 0 && !port_is_suspended(hub, portstatus)) {
+		if (portchange & USB_PORT_STAT_C_SUSPEND)
+			pm_wakeup_event(&udev->dev, 0);
 		goto SuspendCleared;
+	}
 
 	/* see 7.1.7.7; affects power usage, but not budgeting */
 	if (hub_is_superspeed(hub->hdev))
-- 
2.13.5