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drivers: timer: stm32_lptim: load counter after checking for autoreload

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Bug occurs when polling kernel uptime. Uptime was suddenly
jumping because lptim counter was counted twice
(from CNT and ARR registers) in case reload happens between
values are fetched.

Signed-off-by: Cyril Fougeray <cyril.fougeray@worldcoin.org>
This commit is contained in:
Cyril Fougeray 2022-12-15 16:26:52 +01:00 committed by Carles Cufí
parent 0095eed3a1
commit 6b4a4381de
1 changed files with 8 additions and 3 deletions
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11
drivers/timer/stm32_lptim_timer.c
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@ -246,15 +246,20 @@ uint32_t sys_clock_elapsed(void)
k_spinlock_key_t key = k_spin_lock(&lock);
uint32_t lp_time = z_clock_lptim_getcounter();
uint32_t lp_time = 0;
/* In case of counter roll-over, add this value,
* even if the irq has not yet been handled
/* In case of counter roll-over, add the autoreload value,
* even if the irq has not yet been handled.
* Check ARRM flag before loading counter to make
* sure we don't use a counter close to ARR that
* hasn't triggered ARRM yet, which would mistakenly
* account for double the number of ticks.
*/
if ((LL_LPTIM_IsActiveFlag_ARRM(LPTIM) != 0)
&& LL_LPTIM_IsEnabledIT_ARRM(LPTIM) != 0) {
lp_time += LL_LPTIM_GetAutoReload(LPTIM) + 1;
}
lp_time += z_clock_lptim_getcounter();
k_spin_unlock(&lock, key);