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Subject[PATCH 4.4 16/72] Input: mousedev - fix implicit conversion warning
Date
4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Nick Desaulniers <nick.desaulniers@gmail.com>

commit dae1a432ab1fe79ae53129ededeaece35a2dc14d upstream.

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 the PS2 data is really a stream of bytes, let's switch to using u8 type
for it, which silences this warning.

Signed-off-by: Nick Desaulniers <nick.desaulniers@gmail.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/input/mousedev.c | 62 +++++++++++++++++++++++++----------------------
1 file changed, 34 insertions(+), 28 deletions(-)

--- a/drivers/input/mousedev.c
+++ b/drivers/input/mousedev.c
@@ -15,6 +15,7 @@
#define MOUSEDEV_MINORS 31
#define MOUSEDEV_MIX 63

+#include <linux/bitops.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/poll.h>
@@ -103,7 +104,7 @@ struct mousedev_client {
spinlock_t packet_lock;
int pos_x, pos_y;

- signed char ps2[6];
+ u8 ps2[6];
unsigned char ready, buffer, bufsiz;
unsigned char imexseq, impsseq;
enum mousedev_emul mode;
@@ -291,11 +292,10 @@ static void mousedev_notify_readers(stru
}

client->pos_x += packet->dx;
- client->pos_x = client->pos_x < 0 ?
- 0 : (client->pos_x >= xres ? xres : client->pos_x);
+ client->pos_x = clamp_val(client->pos_x, 0, xres);
+
client->pos_y += packet->dy;
- client->pos_y = client->pos_y < 0 ?
- 0 : (client->pos_y >= yres ? yres : client->pos_y);
+ client->pos_y = clamp_val(client->pos_y, 0, yres);

p->dx += packet->dx;
p->dy += packet->dy;
@@ -571,44 +571,50 @@ static int mousedev_open(struct inode *i
return error;
}

-static inline int mousedev_limit_delta(int delta, int limit)
-{
- return delta > limit ? limit : (delta < -limit ? -limit : delta);
-}
-
-static void mousedev_packet(struct mousedev_client *client,
- signed char *ps2_data)
+static void mousedev_packet(struct mousedev_client *client, u8 *ps2_data)
{
struct mousedev_motion *p = &client->packets[client->tail];
+ s8 dx, dy, dz;
+
+ dx = clamp_val(p->dx, -127, 127);
+ p->dx -= dx;
+
+ dy = clamp_val(p->dy, -127, 127);
+ p->dy -= dy;

- ps2_data[0] = 0x08 |
- ((p->dx < 0) << 4) | ((p->dy < 0) << 5) | (p->buttons & 0x07);
- ps2_data[1] = mousedev_limit_delta(p->dx, 127);
- ps2_data[2] = mousedev_limit_delta(p->dy, 127);
- p->dx -= ps2_data[1];
- p->dy -= ps2_data[2];
+ ps2_data[0] = BIT(3);
+ ps2_data[0] |= ((dx & BIT(7)) >> 3) | ((dy & BIT(7)) >> 2);
+ ps2_data[0] |= p->buttons & 0x07;
+ ps2_data[1] = dx;
+ ps2_data[2] = dy;

switch (client->mode) {
case MOUSEDEV_EMUL_EXPS:
- ps2_data[3] = mousedev_limit_delta(p->dz, 7);
- p->dz -= ps2_data[3];
- ps2_data[3] = (ps2_data[3] & 0x0f) | ((p->buttons & 0x18) << 1);
+ dz = clamp_val(p->dz, -7, 7);
+ p->dz -= dz;
+
+ ps2_data[3] = (dz & 0x0f) | ((p->buttons & 0x18) << 1);
client->bufsiz = 4;
break;

case MOUSEDEV_EMUL_IMPS:
- ps2_data[0] |=
- ((p->buttons & 0x10) >> 3) | ((p->buttons & 0x08) >> 1);
- ps2_data[3] = mousedev_limit_delta(p->dz, 127);
- p->dz -= ps2_data[3];
+ dz = clamp_val(p->dz, -127, 127);
+ p->dz -= dz;
+
+ ps2_data[0] |= ((p->buttons & 0x10) >> 3) |
+ ((p->buttons & 0x08) >> 1);
+ ps2_data[3] = dz;
+
client->bufsiz = 4;
break;

case MOUSEDEV_EMUL_PS2:
default:
- ps2_data[0] |=
- ((p->buttons & 0x10) >> 3) | ((p->buttons & 0x08) >> 1);
p->dz = 0;
+
+ ps2_data[0] |= ((p->buttons & 0x10) >> 3) |
+ ((p->buttons & 0x08) >> 1);
+
client->bufsiz = 3;
break;
}
@@ -714,7 +720,7 @@ static ssize_t mousedev_read(struct file
{
struct mousedev_client *client = file->private_data;
struct mousedev *mousedev = client->mousedev;
- signed char data[sizeof(client->ps2)];
+ u8 data[sizeof(client->ps2)];
int retval = 0;

if (!client->ready && !client->buffer && mousedev->exist &&

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