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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Benson Leung <bleung@chromium.org>,
        Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        Bo Hu <bohu@google.com>
Subject: [PATCH 3.18 01/36] Input: do not emit unneeded EV_SYN when suspending
Date:   Mon,  5 Feb 2018 10:23:29 -0800
Message-Id: <20180205182351.842876188@linuxfoundation.org>
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3.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Dmitry Torokhov <dmitry.torokhov@gmail.com>

commit 00159f19a5057cb779146afce1cceede692af346 upstream.

Do not emit EV_SYN/SYN_REPORT on suspend if there were no keys that are
still pressed as we are suspending the device (and in all other cases when
input core is forcibly releasing keys via input_dev_release_keys() call).

Reviewed-by: Benson Leung <bleung@chromium.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Bo Hu <bohu@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/input/input.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/drivers/input/input.c
+++ b/drivers/input/input.c
@@ -668,6 +668,7 @@ EXPORT_SYMBOL(input_close_device);
  */
 static void input_dev_release_keys(struct input_dev *dev)
 {
+	bool need_sync = false;
 	int code;
 
 	if (is_event_supported(EV_KEY, dev->evbit, EV_MAX)) {
@@ -675,9 +676,11 @@ static void input_dev_release_keys(struc
 			if (is_event_supported(code, dev->keybit, KEY_MAX) &&
 			    __test_and_clear_bit(code, dev->key)) {
 				input_pass_event(dev, EV_KEY, code, 0);
+				need_sync = true;
 			}
 		}
-		input_pass_event(dev, EV_SYN, SYN_REPORT, 1);
+		if (need_sync)
+			input_pass_event(dev, EV_SYN, SYN_REPORT, 1);
 	}
 }