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Fix phantom missed IRQ and wrong average latency #6

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Fix phantom missed IRQ and wrong average latency #6

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2383977
Fix code deficiency that will always cause at least one missed IRQ
Hongbo-F Mar 14, 2017
48980da
Fix wrong method of calculating average latency
Hongbo-F Mar 14, 2017
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8 changes: 4 additions & 4 deletions gpio-test/src/gpio-irq-latency-test.c
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Original file line number Diff line number Diff line change
Expand Up @@ -68,10 +68,7 @@ static void test_irq_latency_timer_handler(unsigned long ptr) {
" : GPIO IRQ triggered after > 1 sec, something is fishy.\n");
data->missed_irqs++;
} else {
data->avg_nsecs = data->avg_nsecs ?
(unsigned long)(((unsigned long long)delta.tv_nsec +
(unsigned long long)data->avg_nsecs) >> 1) :
delta.tv_nsec;
data->avg_nsecs = (data->avg_nsecs * data->test_count + delta.tv_nsec) / (data->test_count + 1);

test_ok = 1;
}
Expand Down Expand Up @@ -161,6 +158,9 @@ int __init test_irq_latency_init_module(void) {
test_data.timer.function = test_irq_latency_timer_handler;
add_timer(&test_data.timer);

getnstimeofday(&test_data.gpio_time);
gpio_set_value(test_data.gpio_pin, 0);

printk(KERN_INFO DRV_NAME " : beginning GPIO IRQ latency test (%u passes in %d seconds).\n",
NUM_TESTS, (NUM_TESTS * TEST_INTERVAL) / HZ);

Expand Down