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hwclock: check if estimated frequency is sane

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This commit is contained in:
Miroslav Lichvar
2017-08-22 13:29:48 +02:00
parent 6dad2c24bf
commit 36291b707b
1 changed files with 6 additions and 2 deletions
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8
hwclock.c
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@@ -39,6 +39,9 @@
/* Maximum number of samples per clock */ /* Maximum number of samples per clock */
#define MAX_SAMPLES 16 #define MAX_SAMPLES 16
/* Maximum acceptable frequency offset of the clock */
#define MAX_FREQ_OFFSET (2.0 / 3.0)
struct HCL_Instance_Record { struct HCL_Instance_Record {
/* HW and local reference timestamp */ /* HW and local reference timestamp */
struct timespec hw_ref; struct timespec hw_ref;
@@ -175,8 +178,9 @@ HCL_AccumulateSample(HCL_Instance clock, struct timespec *hw_ts,
clock->n_samples -= best_start; clock->n_samples -= best_start;
/* If the fit doesn't cross the error interval of the last sample, /* If the fit doesn't cross the error interval of the last sample,
throw away all samples and start again */ or the frequency is not sane, drop all samples and start again */
if (fabs(clock->offset) > err) { if (fabs(clock->offset) > err ||
fabs(clock->frequency - 1.0) > MAX_FREQ_OFFSET) {
DEBUG_LOG("HW clock reset"); DEBUG_LOG("HW clock reset");
clock->n_samples = 0; clock->n_samples = 0;
clock->valid_coefs = 0; clock->valid_coefs = 0;