linux-kernel - [PATCH 3.10 095/268] Input: mpr121 - handle multiple bits change of status register

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Date:   Mon, 19 Jun 2017 20:29:54 +0200
From:   Willy Tarreau <w@....eu>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        linux@...ck-us.net
Cc:     Akinobu Mita <akinobu.mita@...il.com>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Oliver Neukum <ONeukum@...e.com>, Jiri Slaby <jslaby@...e.cz>,
        Willy Tarreau <w@....eu>
Subject: [PATCH 3.10 095/268] Input: mpr121 - handle multiple bits change of status register

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

commit 08fea55e37f58371bffc5336a59e55d1f155955a upstream.

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@...il.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc: Oliver Neukum <ONeukum@...e.com>
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
Signed-off-by: Willy Tarreau <w@....eu>
---
 drivers/input/keyboard/mpr121_touchkey.c | 23 ++++++++++++++---------
 1 file changed, 14 insertions(+), 9 deletions(-)

diff --git a/drivers/input/keyboard/mpr121_touchkey.c b/drivers/input/keyboard/mpr121_touchkey.c
index f7f3e9a..d781d53 100644
--- a/drivers/input/keyboard/mpr121_touchkey.c
+++ b/drivers/input/keyboard/mpr121_touchkey.c
@@ -88,7 +88,8 @@ static irqreturn_t mpr_touchkey_interrupt(int irq, void *dev_id)
 	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);
@@ -106,18 +107,22 @@ static irqreturn_t mpr_touchkey_interrupt(int irq, void *dev_id)
 
 	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;
-- 
2.8.0.rc2.1.gbe9624a