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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, Akinobu Mita <akinobu.mita@gmail.com>,
        Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        Sasha Levin <alexander.levin@verizon.com>
Subject: [PATCH 4.9 38/87] Input: mpr121 - handle multiple bits change of status register
Date:   Mon, 13 Nov 2017 13:55:55 +0100
Message-Id: <20171113125618.800612252@linuxfoundation.org>
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4.9-stable review patch.  If anyone has any objections, please let me know.

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

From: Akinobu Mita <akinobu.mita@gmail.com>


[ Upstream commit 08fea55e37f58371bffc5336a59e55d1f155955a ]

This driver reports input events on their interrupts which are triggered
by the sensor's status register changes.  But only single bit change is
reported in the interrupt handler.  So if there are multiple bits are
changed at almost the same time, other press or release events are ignored.

This fixes it by detecting all changed bits in the status register.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/input/keyboard/mpr121_touchkey.c |   23 ++++++++++++++---------
 1 file changed, 14 insertions(+), 9 deletions(-)

--- a/drivers/input/keyboard/mpr121_touchkey.c
+++ b/drivers/input/keyboard/mpr121_touchkey.c
@@ -87,7 +87,8 @@ static irqreturn_t mpr_touchkey_interrup
 	struct mpr121_touchkey *mpr121 = dev_id;
 	struct i2c_client *client = mpr121->client;
 	struct input_dev *input = mpr121->input_dev;
-	unsigned int key_num, key_val, pressed;
+	unsigned long bit_changed;
+	unsigned int key_num;
 	int reg;
 
 	reg = i2c_smbus_read_byte_data(client, ELE_TOUCH_STATUS_1_ADDR);
@@ -105,18 +106,22 @@ static irqreturn_t mpr_touchkey_interrup
 
 	reg &= TOUCH_STATUS_MASK;
 	/* use old press bit to figure out which bit changed */
-	key_num = ffs(reg ^ mpr121->statusbits) - 1;
-	pressed = reg & (1 << key_num);
+	bit_changed = reg ^ mpr121->statusbits;
 	mpr121->statusbits = reg;
+	for_each_set_bit(key_num, &bit_changed, mpr121->keycount) {
+		unsigned int key_val, pressed;
 
-	key_val = mpr121->keycodes[key_num];
+		pressed = reg & BIT(key_num);
+		key_val = mpr121->keycodes[key_num];
 
-	input_event(input, EV_MSC, MSC_SCAN, key_num);
-	input_report_key(input, key_val, pressed);
-	input_sync(input);
+		input_event(input, EV_MSC, MSC_SCAN, key_num);
+		input_report_key(input, key_val, pressed);
+
+		dev_dbg(&client->dev, "key %d %d %s\n", key_num, key_val,
+			pressed ? "pressed" : "released");
 
-	dev_dbg(&client->dev, "key %d %d %s\n", key_num, key_val,
-		pressed ? "pressed" : "released");
+	}
+	input_sync(input);
 
 out:
 	return IRQ_HANDLED;


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