diff options
| -rw-r--r-- | core/cortex-m/timer.c | 16 |
1 files changed, 13 insertions, 3 deletions
diff --git a/core/cortex-m/timer.c b/core/cortex-m/timer.c index de4310a88e..0256d673bc 100644 --- a/core/cortex-m/timer.c +++ b/core/cortex-m/timer.c @@ -96,10 +96,20 @@ void process_timers(int overflow) void udelay(unsigned us) { - timestamp_t deadline = get_time(); + unsigned t0 = __hw_clock_source_read(); - deadline.val += us; - while (get_time().val < deadline.val) {} + /* + * udelay() may be called with interrupts disabled, so we can't rely on + * process_timers() updating the top 32 bits. So handle wraparound + * ourselves rather than calling get_time() and comparing with a + * deadline. + * + * This may fail for delays close to 2^32 us (~4000 sec), because the + * subtraction below can overflow. That's acceptable, because the + * watchdog timer would have tripped long before that anyway. + */ + while (__hw_clock_source_read() - t0 < us) + ; } int timer_arm(timestamp_t tstamp, task_id_t tskid) |