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Fix key delay and repeat, part 2.

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Use sbintime_t timeouts with precision control to get very accurate
timing.  It costs little to always ask for about 1% accuracy, and the
not so new event timer implementation usual delivers that, and when
it can't it gets much closer than our previous coarse timeouts and
buggy simple countdown.

The 2 fastest atkbd repeat rates have periods 34 and 38 msec, and ukbd
pretended to support rates in between these.  This requires
sub-microsecond precision and accuracy even to handle the 4 msec
difference very well, but ukbd asked the timeout subsystem for timeouts
of 25 msec and the buggy simple countdown of this gave a a wide range
of precisions and accuracies depending on HZ and other timer
configuration (sometimes better than 25 msec but usually more like 50
msec).  We now ask for and usually get precision and accuracy of about
1% for each repeat and much better on average.

The 1% accuracy is overkill.  Rounding of 30 cps to 34 msec instead of
33 already gives an error of +2% instead of -1%, and ut AT keyboards on
PS/2 interfaces have similar errors.

A timeout is now scheduled for every keypress and release.  This allows
some simplifications that are not done.  It allows removing the timeout
scheduling for exiting polled mode where it was unsafe in ddb mode.  This
is done.  Exiting polled mode had some problems with extra repeats.  Now
exiting polled mode lets an extra timeout fire and the state is fudged
so that the timeout handler does very little.

The sc->time_ms variable is unsigned to avoid overflow.  Differences of
it need to be signed.  Signed comparisons were emulated by testing an
emulated sign bits.  This only works easily for '<' comparisonss, but
we now need a '<=' comparison.  Change the difference variable to
signed and use a signed comparison.  Using unsigned types here didn't
prevent overflow bugs but just reduced them.  Overflow occurs with
n repeats at the silly repeat period of [U]INT_MAX / n.  The old countdown
had an off by 1 error, and the simplifications would simply count down
1 to 0 and not need to accumulate possibly-large repeat repeats.
This commit is contained in:
Bruce Evans 2016-08-24 05:54:11 +00:00
parent 8f555c7d0a
commit 1a58327bc3
1 changed files with 27 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

40
sys/dev/usb/input/ukbd.c
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@ -163,6 +163,8 @@ struct ukbd_softc {
struct usb_interface *sc_iface;
struct usb_xfer *sc_xfer[UKBD_N_TRANSFER];
sbintime_t sc_co_basetime;
int sc_delay;
uint32_t sc_ntime[UKBD_NKEYCODE];
uint32_t sc_otime[UKBD_NKEYCODE];
uint32_t sc_input[UKBD_IN_BUF_SIZE]; /* input buffer */
@ -182,7 +184,6 @@ struct ukbd_softc {
#define UKBD_FLAG_APPLE_EJECT 0x00000040
#define UKBD_FLAG_APPLE_FN 0x00000080
#define UKBD_FLAG_APPLE_SWAP 0x00000100
#define UKBD_FLAG_TIMER_RUNNING 0x00000200
#define UKBD_FLAG_CTRL_L 0x00000400
#define UKBD_FLAG_CTRL_R 0x00000800
#define UKBD_FLAG_SHIFT_L 0x00001000
@ -393,8 +394,14 @@ ukbd_any_key_pressed(struct ukbd_softc *sc)
static void
ukbd_start_timer(struct ukbd_softc *sc)
{
sc->sc_flags |= UKBD_FLAG_TIMER_RUNNING;
usb_callout_reset(&sc->sc_callout, hz / 40, &ukbd_timeout, sc);
sbintime_t delay, prec;
delay = SBT_1MS * sc->sc_delay;
sc->sc_co_basetime += delay;
/* This is rarely called, so prefer precision to efficiency. */
prec = qmin(delay >> 7, SBT_1MS * 10);
callout_reset_sbt(&sc->sc_callout.co, sc->sc_co_basetime, prec,
ukbd_timeout, sc, C_ABSOLUTE);
}
static void
@ -503,10 +510,11 @@ ukbd_get_key(struct ukbd_softc *sc, uint8_t wait)
static void
ukbd_interrupt(struct ukbd_softc *sc)
{
struct timeval ctv;
uint32_t n_mod;
uint32_t o_mod;
uint32_t now = sc->sc_time_ms;
uint32_t dtime;
int32_t dtime;
uint8_t key;
uint8_t i;
uint8_t j;
@ -564,7 +572,7 @@ rfound: ;
sc->sc_ntime[i] = sc->sc_otime[j];
dtime = (sc->sc_otime[j] - now);
if (!(dtime & 0x80000000)) {
if (dtime > 0) {
/* time has not elapsed */
goto pfound;
}
@ -572,6 +580,15 @@ rfound: ;
break;
}
}
if (j < UKBD_NKEYCODE) {
/* Old key repeating. */
sc->sc_delay = sc->sc_kbd.kb_delay2;
} else {
/* New key. */
microuptime(&ctv);
sc->sc_co_basetime = tvtosbt(ctv);
sc->sc_delay = sc->sc_kbd.kb_delay1;
}
ukbd_put_key(sc, key | KEY_PRESS);
/*
@ -626,7 +643,8 @@ ukbd_timeout(void *arg)
UKBD_LOCK_ASSERT();
sc->sc_time_ms += 25; /* milliseconds */
sc->sc_time_ms += sc->sc_delay;
sc->sc_delay = 0;
ukbd_interrupt(sc);
@ -635,8 +653,6 @@ ukbd_timeout(void *arg)
if (ukbd_any_key_pressed(sc) || (sc->sc_inputs != 0)) {
ukbd_start_timer(sc);
} else {
sc->sc_flags &= ~UKBD_FLAG_TIMER_RUNNING;
}
}
@ -822,10 +838,8 @@ ukbd_intr_callback(struct usb_xfer *xfer, usb_error_t error)
ukbd_interrupt(sc);
if (!(sc->sc_flags & UKBD_FLAG_TIMER_RUNNING)) {
if (ukbd_any_key_pressed(sc)) {
ukbd_start_timer(sc);
}
if (ukbd_any_key_pressed(sc)) {
ukbd_start_timer(sc);
}
case USB_ST_SETUP:
@ -2016,7 +2030,7 @@ ukbd_poll(keyboard_t *kbd, int on)
sc->sc_poll_thread = curthread;
} else {
sc->sc_flags &= ~UKBD_FLAG_POLLING;
ukbd_start_timer(sc); /* start timer */
sc->sc_delay = 0;
}
UKBD_UNLOCK();