diff options
| -rw-r--r-- | common/timer.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/common/timer.c b/common/timer.c index 0764fb7e1b..42c08a8de5 100644 --- a/common/timer.c +++ b/common/timer.c @@ -143,9 +143,16 @@ void timer_cancel(task_id_t tskid) */ } +/* + * For us < (2^31 - task scheduling latency)(~ 2147 sec), this function will + * sleep for at least us, and no more than 2*us. As us approaches 2^32-1, the + * probability of delay longer than 2*us (and possibly infinite delay) + * increases. + */ void usleep(unsigned us) { uint32_t evt = 0; + uint32_t t0 = __hw_clock_source_read(); /* If task scheduling has not started, just delay */ if (!task_start_called()) { @@ -156,7 +163,8 @@ void usleep(unsigned us) ASSERT(us); do { evt |= task_wait_event(us); - } while (!(evt & TASK_EVENT_TIMER)); + } while (!(evt & TASK_EVENT_TIMER) && + ((__hw_clock_source_read() - t0) < us)); /* Re-queue other events which happened in the meanwhile */ if (evt) |