ea546c789b
Rename sched_tasks_busy() to sched_check_set_tasks_busy() and change it to only return true if tasks are active (running or requested) for two consecutive calls. This makes it less likely that timers will yield to tasks except when tasks really are notably backlogged. This also makes it less likely that multiple steppers controlling the same rail will be interrupted by tasks mid-step. This should slightly improve the timing, and make it less likely that a halt during homing/probing will occur with these steppers taking a different number of total steps. Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
84 lines
2.5 KiB
C
84 lines
2.5 KiB
C
// Generic interrupt based timer helper functions
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//
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// Copyright (C) 2017 Kevin O'Connor <kevin@koconnor.net>
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//
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// This file may be distributed under the terms of the GNU GPLv3 license.
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#include "autoconf.h" // CONFIG_CLOCK_FREQ
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#include "board/irq.h" // irq_disable
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#include "board/misc.h" // timer_from_us
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#include "board/timer_irq.h" // timer_dispatch_many
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#include "command.h" // shutdown
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#include "sched.h" // sched_timer_dispatch
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DECL_CONSTANT("CLOCK_FREQ", CONFIG_CLOCK_FREQ);
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// Return the number of clock ticks for a given number of microseconds
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uint32_t
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timer_from_us(uint32_t us)
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{
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return us * (CONFIG_CLOCK_FREQ / 1000000);
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}
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// Return true if time1 is before time2. Always use this function to
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// compare times as regular C comparisons can fail if the counter
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// rolls over.
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uint8_t
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timer_is_before(uint32_t time1, uint32_t time2)
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{
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return (int32_t)(time1 - time2) < 0;
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}
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static uint32_t timer_repeat_until;
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#define TIMER_IDLE_REPEAT_TICKS timer_from_us(500)
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#define TIMER_REPEAT_TICKS timer_from_us(100)
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#define TIMER_MIN_TRY_TICKS timer_from_us(2)
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#define TIMER_DEFER_REPEAT_TICKS timer_from_us(5)
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// Invoke timers - called from board irq code.
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uint32_t
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timer_dispatch_many(void)
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{
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uint32_t tru = timer_repeat_until;
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for (;;) {
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// Run the next software timer
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uint32_t next = sched_timer_dispatch();
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uint32_t now = timer_read_time();
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int32_t diff = next - now;
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if (diff > (int32_t)TIMER_MIN_TRY_TICKS)
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// Schedule next timer normally.
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return next;
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if (unlikely(timer_is_before(tru, now))) {
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// Check if there are too many repeat timers
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if (diff < (int32_t)(-timer_from_us(1000)))
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try_shutdown("Rescheduled timer in the past");
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if (sched_check_set_tasks_busy()) {
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timer_repeat_until = now + TIMER_REPEAT_TICKS;
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return now + TIMER_DEFER_REPEAT_TICKS;
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}
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timer_repeat_until = tru = now + TIMER_IDLE_REPEAT_TICKS;
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}
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// Next timer in the past or near future - wait for it to be ready
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irq_enable();
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while (unlikely(diff > 0))
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diff = next - timer_read_time();
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irq_disable();
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}
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}
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// Make sure timer_repeat_until doesn't wrap 32bit comparisons
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void
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timer_task(void)
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{
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uint32_t now = timer_read_time();
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irq_disable();
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if (timer_is_before(timer_repeat_until, now))
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timer_repeat_until = now;
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irq_enable();
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}
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DECL_TASK(timer_task);
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