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node-driver: Factor on_timeout execution delay into current_time

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This commit is contained in:
Carlos Rafael Giani 2026-05-26 11:33:09 +02:00
parent 3a9ffbb56d
commit cc1cc27c34
1 changed files with 19 additions and 5 deletions
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24
spa/plugins/support/node-driver.c
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@ -358,6 +358,7 @@ static void on_timeout(struct spa_source *source)
{
struct impl *this = source->data;
uint64_t expirations, nsec, duration, current_time, current_position, position;
uint64_t time_since_nsec;
uint32_t rate;
double corr = 1.0, err = 0.0;
int res;
@ -404,11 +405,22 @@ static void on_timeout(struct spa_source *source)
* and this->clock->position values are correct anymore. (Timer
* cancellations happen when the realtime clock is being used by
* this driver and the user modified the realtime clock for example.)
*
* time_since_nsec is an extra factor that corrects inaccuracies when
* the on_timeout() callback is executed with a slight delay. This
* delay is factored into current_time and later in the err value,
* which means that the DLL has to compensate for it. time_since_nsec
* estimates the delay, and subtracts that estimation, leading to
* a reduced impact on current_time, and thus, the DLL does not have
* to compensate as much, which increases the control loop stability.
*/
if (this->props.freewheel || SPA_UNLIKELY(timer_was_canceled))
if (this->props.freewheel || SPA_UNLIKELY(timer_was_canceled)) {
nsec = gettime_nsec(this, this->timer_clockid);
else
time_since_nsec = 0;
} else {
nsec = this->next_time;
time_since_nsec = gettime_nsec(this, this->timer_clockid) - this->next_time;
}
/* "tracking" means that the driver is following a clock that is not
* usable by timerfd. It is an entirely separate clock, for example,
@ -416,10 +428,12 @@ static void on_timeout(struct spa_source *source)
* always the monotonic clock, and this->props.clock_id is that entirely
* separate clock. If tracking is false, then this->props.clock_id
* equals timer_clockid, so "nsec" can directly be used as the current
* driver clock time in that case. */
if (this->tracking)
* driver clock time in that case.
* (See the comment above for the purpose of time_since_nsec.) */
if (this->tracking) {
current_time = gettime_nsec(this, this->props.clock_id);
else
current_time -= SPA_LIKELY(current_time >= time_since_nsec) ? time_since_nsec : 0;
} else
current_time = nsec;
current_position = scale_u64(current_time, rate, SPA_NSEC_PER_SEC);