kinetis: timer_set_absolute randomly misses its target #8532
Description
Description
Using the test application introduced in #8531, it was discovered that the implementation of timer_set_absolute sometimes misses its target when using the LPTMR hardware timer. The error seem timing dependent and occurs randomly while running the test.
Steps to reproduce the issue
Build the test application in #8531 with
CFLAGS='-DTIM_TEST_DEV=TIMER_DEV\(2\) -DTIM_TEST_FREQ=32768' make -j9 BOARD=mulle flash
Expected results
All absolute min, max, mean values < 100, variance < 100
Actual results
2018-02-07 16:48:13,928 - INFO # === timer_set_absolute ===
2018-02-07 16:48:13,931 - INFO # interval count sum sum_sq min max mean variance
2018-02-07 16:48:13,935 - INFO # 1: 3046 145117 6914339 47 48 47 60
2018-02-07 16:48:13,944 - INFO # 2: 3090 145823 6882181 46 48 47 18
2018-02-07 16:48:13,947 - INFO # 3: 3037 145032 6926590 47 49 47 71
2018-02-07 16:48:13,950 - INFO # 4: 2955 139639 6599227 46 48 47 24
2018-02-07 16:48:13,960 - INFO # 5: 3050 174270 833852828 47 28756 57 270233 <=== SIC!
2018-02-07 16:48:13,961 - INFO # 6: 3017 142338 6715790 46 48 47 16
2018-02-07 16:48:13,976 - INFO # 7: 3008 115115 802297129 -28204 48 38 265365 <=== SIC!
2018-02-07 16:48:13,976 - INFO # 8: 3040 143426 6767262 46 48 47 17
2018-02-07 16:48:13,977 - INFO # 9: 3017 173481 887463109 47 29675 57 291001 <=== SIC!
2018-02-07 16:48:13,992 - INFO # 10: 3023 138443 1251241713 -30107 13464 45 412018 <=== SIC!
2018-02-07 16:48:13,993 - INFO # 11: 3092 147462 7033344 47 49 47 65
2018-02-07 16:48:13,993 - INFO # 12: 3010 142046 6703862 46 48 47 18
2018-02-07 16:48:14,009 - INFO # 13: 2994 142771 6808789 47 49 47 65
2018-02-07 16:48:14,012 - INFO # 14: 3072 144944 6839284 46 48 47 17
2018-02-07 16:48:14,024 - INFO # 15: 3122 148867 7099137 47 49 47 64
2018-02-07 16:48:14,027 - INFO # 16: 3038 146240 15615240 46 2976 48 2836 <=== SIC!
2018-02-07 16:48:14,031 - INFO # 17: 2978 142013 6772875 47 49 47 65
2018-02-07 16:48:14,041 - INFO # 18: 3067 166728 493778432 46 22067 54 158132 <=== SIC!
Versions
arm-none-eabi-gcc: arm-none-eabi-gcc (Gentoo 7.2.0-r1 p1.1) 7.2.0
arm-none-eabi-newlib: "2.5.0"
RIOT repo: same branch as in #8531