linux-kernel - [PATCH v3] Input: mousedev - fix implicit conversion warning

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Message-Id: <20170526154029.9405-1-nick.desaulniers@gmail.com>
Date:   Fri, 26 May 2017 08:40:28 -0700
From:   Nick Desaulniers <nick.desaulniers@...il.com>
To:     unlisted-recipients:; (no To-header on input)
Cc:     gregkh@...uxfoundation.org,
        Nick Desaulniers <nick.desaulniers@...il.com>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        linux-input@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v3] Input: mousedev - fix implicit conversion warning

Clang warns:

drivers/input/mousedev.c:653:63: error: implicit conversion from 'int'
to 'signed char' changes value from 200 to -56
[-Wconstant-conversion]
  client->ps2[1] = 0x60; client->ps2[2] = 3; client->ps2[3] = 200;
                                                            ~ ^~~

As far as I can tell, from

http://www.computer-engineering.org/ps2mouse/

Under "Command Set" > "0xE9 (Status Request)"

the value 200 is a valid sample rate. Using unsigned char, rather than
signed char, for client->ps2 silences this warning.

Signed-off-by: Nick Desaulniers <nick.desaulniers@...il.com>
---
* Additionally change function signature for the lone function dealing
  with ps2 data.

 drivers/input/mousedev.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/input/mousedev.c b/drivers/input/mousedev.c
index 0e0ff84088fd..0e31a109b1b4 100644
--- a/drivers/input/mousedev.c
+++ b/drivers/input/mousedev.c
@@ -103,7 +103,7 @@ struct mousedev_client {
 	spinlock_t packet_lock;
 	int pos_x, pos_y;
 
-	signed char ps2[6];
+	unsigned char ps2[6];
 	unsigned char ready, buffer, bufsiz;
 	unsigned char imexseq, impsseq;
 	enum mousedev_emul mode;
@@ -577,7 +577,7 @@ static inline int mousedev_limit_delta(int delta, int limit)
 }
 
 static void mousedev_packet(struct mousedev_client *client,
-			    signed char *ps2_data)
+	unsigned char *ps2_data)
 {
 	struct mousedev_motion *p = &client->packets[client->tail];
 
-- 
2.11.0