Input: joystick - use ktime for measuring timing
The current codes in gameport and analog joystick drivers for the time
accounting have a long-standing problem when the system is running
with CPU freq; since the timing is measured via TSC or sample counter,
the calculation isn't reliable.
In this patch, as a simple fix, use the standard ktime to measure the
timing. In case where no high resolution timer is available,
use_ktime bool option is provided to both modules. Setting
use_ktime=false switches to the old methods.
Tested-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
diff --git a/drivers/input/joystick/analog.c b/drivers/input/joystick/analog.c
index ab0fdcd..4284080 100644
--- a/drivers/input/joystick/analog.c
+++ b/drivers/input/joystick/analog.c
@@ -36,6 +36,7 @@
#include <linux/gameport.h>
#include <linux/jiffies.h>
#include <linux/timex.h>
+#include <linux/timekeeping.h>
#define DRIVER_DESC "Analog joystick and gamepad driver"
@@ -43,6 +44,10 @@
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL");
+static bool use_ktime = true;
+module_param(use_ktime, bool, 0400);
+MODULE_PARM_DESC(use_ktime, "Use ktime for measuring I/O speed");
+
/*
* Option parsing.
*/
@@ -171,6 +176,25 @@
#warning Precise timer not defined for this architecture.
#endif
+static inline u64 get_time(void)
+{
+ if (use_ktime) {
+ return ktime_get_ns();
+ } else {
+ unsigned int x;
+ GET_TIME(x);
+ return x;
+ }
+}
+
+static inline unsigned int delta(u64 x, u64 y)
+{
+ if (use_ktime)
+ return y - x;
+ else
+ return DELTA((unsigned int)x, (unsigned int)y);
+}
+
/*
* analog_decode() decodes analog joystick data and reports input events.
*/
@@ -226,7 +250,8 @@
static int analog_cooked_read(struct analog_port *port)
{
struct gameport *gameport = port->gameport;
- unsigned int time[4], start, loop, now, loopout, timeout;
+ u64 time[4], start, loop, now;
+ unsigned int loopout, timeout;
unsigned char data[4], this, last;
unsigned long flags;
int i, j;
@@ -236,7 +261,7 @@
local_irq_save(flags);
gameport_trigger(gameport);
- GET_TIME(now);
+ now = get_time();
local_irq_restore(flags);
start = now;
@@ -249,16 +274,16 @@
local_irq_disable();
this = gameport_read(gameport) & port->mask;
- GET_TIME(now);
+ now = get_time();
local_irq_restore(flags);
- if ((last ^ this) && (DELTA(loop, now) < loopout)) {
+ if ((last ^ this) && (delta(loop, now) < loopout)) {
data[i] = last ^ this;
time[i] = now;
i++;
}
- } while (this && (i < 4) && (DELTA(start, now) < timeout));
+ } while (this && (i < 4) && (delta(start, now) < timeout));
this <<= 4;
@@ -266,7 +291,7 @@
this |= data[i];
for (j = 0; j < 4; j++)
if (data[i] & (1 << j))
- port->axes[j] = (DELTA(start, time[i]) << ANALOG_FUZZ_BITS) / port->loop;
+ port->axes[j] = (delta(start, time[i]) << ANALOG_FUZZ_BITS) / port->loop;
}
return -(this != port->mask);
@@ -365,31 +390,39 @@
static void analog_calibrate_timer(struct analog_port *port)
{
struct gameport *gameport = port->gameport;
- unsigned int i, t, tx, t1, t2, t3;
+ unsigned int i, t, tx;
+ u64 t1, t2, t3;
unsigned long flags;
- local_irq_save(flags);
- GET_TIME(t1);
+ if (use_ktime) {
+ port->speed = 1000000;
+ } else {
+ local_irq_save(flags);
+ t1 = get_time();
#ifdef FAKE_TIME
- analog_faketime += 830;
+ analog_faketime += 830;
#endif
- mdelay(1);
- GET_TIME(t2);
- GET_TIME(t3);
- local_irq_restore(flags);
+ mdelay(1);
+ t2 = get_time();
+ t3 = get_time();
+ local_irq_restore(flags);
- port->speed = DELTA(t1, t2) - DELTA(t2, t3);
+ port->speed = delta(t1, t2) - delta(t2, t3);
+ }
tx = ~0;
for (i = 0; i < 50; i++) {
local_irq_save(flags);
- GET_TIME(t1);
- for (t = 0; t < 50; t++) { gameport_read(gameport); GET_TIME(t2); }
- GET_TIME(t3);
+ t1 = get_time();
+ for (t = 0; t < 50; t++) {
+ gameport_read(gameport);
+ t2 = get_time();
+ }
+ t3 = get_time();
local_irq_restore(flags);
udelay(i);
- t = DELTA(t1, t2) - DELTA(t2, t3);
+ t = delta(t1, t2) - delta(t2, t3);
if (t < tx) tx = t;
}