linux-kernel - [PATCH 1/8] Input: st1232 - simplify parsing of read buffer

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Message-Id: <20191022195622.66976-2-dmitry.torokhov@gmail.com>
Date:   Tue, 22 Oct 2019 12:56:15 -0700
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Martin Kepplinger <martink@...teo.de>
Cc:     Dixit Parmar <dixitparmar19@...il.com>,
        Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>,
        Matthias Fend <matthias.fend@...fvision.net>,
        linux-input@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 1/8] Input: st1232 - simplify parsing of read buffer

Avoid complex 2-variable loop when parsing touchscreen data to make the
code clearer.

Acked-by: Martin Kepplinger <martink@...teo.de>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
---

 drivers/input/touchscreen/st1232.c | 50 +++++++++++++++---------------
 1 file changed, 25 insertions(+), 25 deletions(-)

diff --git a/drivers/input/touchscreen/st1232.c b/drivers/input/touchscreen/st1232.c
index 1139714e72e2..47033ef3749a 100644
--- a/drivers/input/touchscreen/st1232.c
+++ b/drivers/input/touchscreen/st1232.c
@@ -57,38 +57,38 @@ static int st1232_ts_read_data(struct st1232_ts_data *ts)
 {
 	struct st1232_ts_finger *finger = ts->finger;
 	struct i2c_client *client = ts->client;
-	struct i2c_msg msg[2];
-	int error;
-	int i, y;
 	u8 start_reg = ts->chip_info->start_reg;
-	u8 *buf = ts->read_buf;
-
-	/* read touchscreen data */
-	msg[0].addr = client->addr;
-	msg[0].flags = 0;
-	msg[0].len = 1;
-	msg[0].buf = &start_reg;
-
-	msg[1].addr = ts->client->addr;
-	msg[1].flags = I2C_M_RD;
-	msg[1].len = ts->read_buf_len;
-	msg[1].buf = buf;
+	struct i2c_msg msg[] = {
+		{
+			.addr	= client->addr,
+			.len	= sizeof(start_reg),
+			.buf	= &start_reg,
+		},
+		{
+			.addr	= client->addr,
+			.flags	= I2C_M_RD,
+			.len	= ts->read_buf_len,
+			.buf	= ts->read_buf,
+		}
+	};
+	int ret;
+	int i;
+	u8 *buf;
 
-	error = i2c_transfer(client->adapter, msg, 2);
-	if (error < 0)
-		return error;
+	ret = i2c_transfer(client->adapter, msg, ARRAY_SIZE(msg));
+	if (ret != ARRAY_SIZE(msg))
+		return ret < 0 ? ret : -EIO;
 
-	for (i = 0, y = 0; i < ts->chip_info->max_fingers; i++, y += 3) {
-		finger[i].is_valid = buf[i + y] >> 7;
+	for (i = 0; i < ts->chip_info->max_fingers; i++) {
+		buf = &ts->read_buf[i * 4];
+		finger[i].is_valid = buf[0] >> 7;
 		if (finger[i].is_valid) {
-			finger[i].x = ((buf[i + y] & 0x0070) << 4) |
-					buf[i + y + 1];
-			finger[i].y = ((buf[i + y] & 0x0007) << 8) |
-					buf[i + y + 2];
+			finger[i].x = ((buf[0] & 0x70) << 4) | buf[1];
+			finger[i].y = ((buf[0] & 0x07) << 8) | buf[2];
 
 			/* st1232 includes a z-axis / touch strength */
 			if (ts->chip_info->have_z)
-				finger[i].t = buf[i + 6];
+				finger[i].t = ts->read_buf[i + 6];
 		}
 	}
 
-- 
2.23.0.866.gb869b98d4c-goog