From 8980f190947ba29f23110408e712444884b74251 Mon Sep 17 00:00:00 2001
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
Date: Sun, 19 Mar 2023 21:36:36 -0700
Subject: [PATCH] Input: focaltech - use explicitly signed char type
Git-commit: 8980f190947ba29f23110408e712444884b74251
Patch-mainline: v6.3-rc5
References: git-fixes

The recent change of -funsigned-char causes additions of negative
numbers to become additions of large positive numbers, leading to wrong
calculations of mouse movement. Change these casts to be explicitly
signed, to take into account negative offsets.

Fixes: 3bc753c06dd0 ("kbuild: treat char as always unsigned")
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Cc: stable@vger.kernel.org
Link: https://bugzilla.kernel.org/show_bug.cgi?id=217211
Link: https://lore.kernel.org/r/20230318133010.1285202-1-Jason@zx2c4.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/input/mouse/focaltech.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/input/mouse/focaltech.c b/drivers/input/mouse/focaltech.c
index 6fd5fff0cbff..c74b99077d16 100644
--- a/drivers/input/mouse/focaltech.c
+++ b/drivers/input/mouse/focaltech.c
@@ -202,8 +202,8 @@ static void focaltech_process_rel_packet(struct psmouse *psmouse,
 	state->pressed = packet[0] >> 7;
 	finger1 = ((packet[0] >> 4) & 0x7) - 1;
 	if (finger1 < FOC_MAX_FINGERS) {
-		state->fingers[finger1].x += (char)packet[1];
-		state->fingers[finger1].y += (char)packet[2];
+		state->fingers[finger1].x += (s8)packet[1];
+		state->fingers[finger1].y += (s8)packet[2];
 	} else {
 		psmouse_err(psmouse, "First finger in rel packet invalid: %d\n",
 			    finger1);
@@ -218,8 +218,8 @@ static void focaltech_process_rel_packet(struct psmouse *psmouse,
 	 */
 	finger2 = ((packet[3] >> 4) & 0x7) - 1;
 	if (finger2 < FOC_MAX_FINGERS) {
-		state->fingers[finger2].x += (char)packet[4];
-		state->fingers[finger2].y += (char)packet[5];
+		state->fingers[finger2].x += (s8)packet[4];
+		state->fingers[finger2].y += (s8)packet[5];
 	}
 }
 
-- 
2.35.3