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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, Caleb Connolly <caleb@connolly.tech>,
        Andi Shyti <andi@etezian.org>,
        Dmitry Torokhov <dmitry.torokhov@gmail.com>
Subject: [PATCH 4.19 23/57] Input: s6sy761 - fix coordinate read bit shift
Date:   Mon, 26 Apr 2021 09:29:20 +0200
Message-Id: <20210426072821.364580076@linuxfoundation.org>
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From: Caleb Connolly <caleb@connolly.tech>

commit 30b3f68715595dee7fe4d9bd91a2252c3becdf0a upstream.

The touch coordinate register contains the following:

        byte 3             byte 2             byte 1
+--------+--------+ +-----------------+ +-----------------+
|        |        | |                 | |                 |
| X[3:0] | Y[3:0] | |     Y[11:4]     | |     X[11:4]     |
|        |        | |                 | |                 |
+--------+--------+ +-----------------+ +-----------------+

Bytes 2 and 1 need to be shifted left by 4 bits, the least significant
nibble of each is stored in byte 3. Currently they are only
being shifted by 3 causing the reported coordinates to be incorrect.

This matches downstream examples, and has been confirmed on my
device (OnePlus 7 Pro).

Fixes: 0145a7141e59 ("Input: add support for the Samsung S6SY761 touchscreen")
Signed-off-by: Caleb Connolly <caleb@connolly.tech>
Reviewed-by: Andi Shyti <andi@etezian.org>
Link: https://lore.kernel.org/r/20210305185710.225168-1-caleb@connolly.tech
Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/input/touchscreen/s6sy761.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/input/touchscreen/s6sy761.c
+++ b/drivers/input/touchscreen/s6sy761.c
@@ -145,8 +145,8 @@ static void s6sy761_report_coordinates(s
 	u8 major = event[4];
 	u8 minor = event[5];
 	u8 z = event[6] & S6SY761_MASK_Z;
-	u16 x = (event[1] << 3) | ((event[3] & S6SY761_MASK_X) >> 4);
-	u16 y = (event[2] << 3) | (event[3] & S6SY761_MASK_Y);
+	u16 x = (event[1] << 4) | ((event[3] & S6SY761_MASK_X) >> 4);
+	u16 y = (event[2] << 4) | (event[3] & S6SY761_MASK_Y);
 
 	input_mt_slot(sdata->input, tid);