Re: [PATCH v4] Input: mousedev - fix implicit conversion warning
From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Date: 2017-06-25 18:06:15
Also in:
lkml
Subsystem:
input (keyboard, mouse, joystick, touchscreen) drivers, the rest · Maintainers:
Dmitry Torokhov, Linus Torvalds
Hi Nick, On Mon, May 29, 2017 at 10:41:51PM -0700, Nick Desaulniers wrote:
quoted hunk ↗ jump to hunk
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. Also moves some reused logic into a helper function. Signed-off-by: Nick Desaulniers <redacted> --- What's new in v4: * replace mousedev_limit_delta() with update_clamped() that also updates the ps2_data and delta values. The use of the temporary val should avoid integral conversion and promotion issues. drivers/input/mousedev.c | 23 +++++++++++------------ 1 file changed, 11 insertions(+), 12 deletions(-)diff --git a/drivers/input/mousedev.c b/drivers/input/mousedev.c index 0e0ff84088fd..e645b8c6f2cb 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;@@ -571,27 +571,27 @@ static int mousedev_open(struct inode *inode, struct file *file) return error; } -static inline int mousedev_limit_delta(int delta, int limit) +static inline void +update_clamped(unsigned char *ps2_data, int *delta, int limit) { - return delta > limit ? limit : (delta < -limit ? -limit : delta); + int val = *delta > limit ? limit : (*delta < -limit ? -limit : *delta); + *ps2_data = (unsigned char) val; + *delta -= val;
Since the time the code was written we got nice helpers to clamp the
values. Does the following work for you or it still leaves clang
unhappy?
Thanks.
--
Dmitry
Input: mousedev - fix implicit conversion warning
From: Nick Desaulniers <redacted>
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 <redacted>
Patchwork-Id: 9753771
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
---
drivers/input/mousedev.c | 60 +++++++++++++++++++++++++---------------------
1 file changed, 32 insertions(+), 28 deletions(-)
diff --git a/drivers/input/mousedev.c b/drivers/input/mousedev.c
index 0e0ff84088fd..6ef0c5314f69 100644
--- 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(struct mousedev *mousedev, } 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 +571,48 @@ static int mousedev_open(struct inode *inode, struct file *file) 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; 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 +718,7 @@ static ssize_t mousedev_read(struct file *file, char __user *buffer, { 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 &&