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authorDmitry Osipenko <digetx@gmail.com>2016-06-06 16:59:30 +0100
committerPeter Maydell <peter.maydell@linaro.org>2016-06-06 16:59:30 +0100
commite91171e30235ae99ab8060988aa3c9536692bba8 (patch)
tree1195474d5a8dd172bcb37f505f4c0a2518b53936 /hw/core/Makefile.objs
parent2a0ee672c9f0a13fd0535d831366670561b4586e (diff)
hw/ptimer: Fix issues caused by the adjusted timer limit value
Multiple issues here related to the timer with a adjusted .limit value: 1) ptimer_get_count() returns incorrect counter value for the disabled timer after loading the counter with a small value, because adjusted limit value is used instead of the original. For instance: 1) ptimer_stop(t) 2) ptimer_set_period(t, 1) 3) ptimer_set_limit(t, 0, 1) 4) ptimer_get_count(t) <-- would return 10000 instead of 0 2) ptimer_get_count() might return incorrect value for the timer running with a adjusted limit value. For instance: 1) ptimer_stop(t) 2) ptimer_set_period(t, 1) 3) ptimer_set_limit(t, 10, 1) 4) ptimer_run(t) 5) ptimer_get_count(t) <-- might return value > 10 3) Neither ptimer_set_period() nor ptimer_set_freq() are adjusting the limit value, so it is still possible to make timer timeout value arbitrary small. For instance: 1) ptimer_set_period(t, 10000) 2) ptimer_set_limit(t, 1, 0) 3) ptimer_set_period(t, 1) <-- bypass limit correction Fix all of the above issues by adjusting timer period instead of the limit. Perform the adjustment for periodic timer only. Use the delta value instead of the limit to make decision whether adjustment is required, as limit could be altered while timer is running, resulting in incorrect value returned by ptimer_get_count. Signed-off-by: Dmitry Osipenko <digetx@gmail.com> Reviewed-by: Peter Crosthwaite <crosthwaite.peter@gmail.com> Message-id: cd141f74f5737480ec586b9c7d18cce1d69884e2.1464367869.git.digetx@gmail.com Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
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