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[PATCH] HID: usbhid: get/put around clearing needs_remote_wakeup

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  [PATCH] HID: usbhid: get/put around clearing needs_remote_wakeup Dmitry Torokhov <dmitry.torokhov@gmail.com> - 2017-09-08 19:50 +0200
    Re: [PATCH] HID: usbhid: get/put around clearing needs_remote_wakeup Oliver Neukum <oneukum@suse.com> - 2017-09-09 09:40 +0200

#1729127 — [PATCH] HID: usbhid: get/put around clearing needs_remote_wakeup

From: Benson Leung <bleung@chromium.org>

usbhid->intf->needs_remote_wakeup is set when a device is opened, and is
cleared when a device is closed.

In usbhid_open, usb_autopm_get_interface is called before setting the
needs_remote_wakeup flag, and usb_autopm_put_interface is called after
hid_start_in. However, when the device is closed in usbhid_close, we
simply reset the flag and the device stays awake even though it could be
suspended.

This patch adds calls to usb_autopm_get_interface and
usb_autopm_put_interface when we reset usbhid->intf->needs_remote_wakeup
flag, giving the system chance to put the device to sleep.

Signed-off-by: Benson Leung <bleung@chromium.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
---
 drivers/hid/usbhid/hid-core.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/hid/usbhid/hid-core.c b/drivers/hid/usbhid/hid-core.c
index 089bad8a9a21..174d87f0e3e6 100644
--- a/drivers/hid/usbhid/hid-core.c
+++ b/drivers/hid/usbhid/hid-core.c
@@ -729,6 +729,7 @@ static int usbhid_open(struct hid_device *hid)
 static void usbhid_close(struct hid_device *hid)
 {
 	struct usbhid_device *usbhid = hid->driver_data;
+	int autopm_error;
 
 	/*
 	 * Make sure we don't restart data acquisition due to
@@ -745,8 +746,14 @@ static void usbhid_close(struct hid_device *hid)
 		return;
 
 	hid_cancel_delayed_stuff(usbhid);
+
+	autopm_error = usb_autopm_get_interface(usbhid->intf);
+
 	usb_kill_urb(usbhid->urbin);
 	usbhid->intf->needs_remote_wakeup = 0;
+
+	if (!autopm_error)
+		usb_autopm_put_interface(usbhid->intf);
 }
 
 /*
@@ -1176,13 +1183,18 @@ static int usbhid_start(struct hid_device *hid)
 static void usbhid_stop(struct hid_device *hid)
 {
 	struct usbhid_device *usbhid = hid->driver_data;
+	int autopm_error;
 
 	if (WARN_ON(!usbhid))
 		return;
 
 	if (hid->quirks & HID_QUIRK_ALWAYS_POLL) {
 		clear_bit(HID_IN_POLLING, &usbhid->iofl);
+
+		autopm_error = usb_autopm_get_interface(usbhid->intf);
 		usbhid->intf->needs_remote_wakeup = 0;
+		if (!autopm_error)
+			usb_autopm_put_interface(usbhid->intf);
 	}
 
 	clear_bit(HID_STARTED, &usbhid->iofl);
-- 
2.14.1.581.gf28d330327-goog


-- 
Dmitry

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#1729403

Am Freitag, den 08.09.2017, 10:43 -0700 schrieb Dmitry Torokhov:
> From: Benson Leung <bleung@chromium.org>
> 
> usbhid->intf->needs_remote_wakeup is set when a device is opened, and is
> cleared when a device is closed.
> 
> In usbhid_open, usb_autopm_get_interface is called before setting the
> needs_remote_wakeup flag, and usb_autopm_put_interface is called after
> hid_start_in. However, when the device is closed in usbhid_close, we
> simply reset the flag and the device stays awake even though it could be
> suspended.

Hi,

but if the device is asleep, we do not want to wake it just to reset
the flag. Please use the no resume varieties. They did not exist when this
code was written and that is the reason behind the current code.

As it is your patch does more harm than good.

	Regards
		Oliver

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