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| author | Shawn Nematbakhsh <shawnn@chromium.org> | 2016-11-09 10:23:17 -0800 |
|---|---|---|
| committer | chrome-bot <chrome-bot@chromium.org> | 2016-11-09 21:14:09 -0800 |
| commit | 92d91adbdb38e5639c200ad65c4651274a8d07f9 (patch) | |
| tree | 31b9b70ff6484ba67b7e7945c01d0eee81909da0 /chip/npcx/clock.c | |
| parent | ebdb6a62aa46f144bdb24da2eea3677ba4329482 (diff) | |
| download | chrome-ec-92d91adbdb38e5639c200ad65c4651274a8d07f9.tar.gz | |
npcx: hwtimer: Fix 'slow' timer count just before overflow
If our 32-bit usec timer is close to overflow, we may deep sleep several
times in succession without making any adjustment to our count, causing
deadlines on the other side (eg. HOOK_TICK expiration) to be reached much
slower than expected. Avoid this by not entering deep sleep if our timer
is about to overflow. This will result in a <= HOOK_TICK_INTERVAL (200ms
interval) period of not entering deep sleep, every ~4300 seconds.
BUG=chrome-os-partner:59240
BRANCH=gru
TEST=Verify 3x kevin units survive 16 hours in S3 without EC watchdog.
Change-Id: I2126458be8820f78212e19c2bb79242ff1194f6f
Signed-off-by: Shawn Nematbakhsh <shawnn@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/409673
Commit-Ready: Shawn N <shawnn@chromium.org>
Tested-by: Shawn N <shawnn@chromium.org>
Reviewed-by: Shawn N <shawnn@chromium.org>
Diffstat (limited to 'chip/npcx/clock.c')
| -rw-r--r-- | chip/npcx/clock.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/chip/npcx/clock.c b/chip/npcx/clock.c index 718d7733b7..196248c592 100644 --- a/chip/npcx/clock.c +++ b/chip/npcx/clock.c @@ -312,6 +312,13 @@ void __idle(void) /* Do we have enough time before next event to deep sleep. */ if (DEEP_SLEEP_ALLOWED && + /* + * Our HW timer doesn't tick in deep sleep - we do manual + * adjustment based on sleep duration after wake. Avoid + * the tricky overflow case by waiting out the period just + * before overflow. + */ + next_evt != EVT_MAX_EXPIRED_US && /* Ensure event hasn't already expired */ next_evt > t0.le.lo && /* Ensure we have sufficient time before expiration */ |