1fb9b7d29d
The C1E/HPET bug reports on AMDX2/RS690 systems where tracked down to a too small value of the HPET minumum delta for programming an event. The clockevents code needs to enforce an interrupt event on the clock event device in some cases. The enforcement code was stupid and naive, as it just added the minimum delta to the current time and tried to reprogram the device. When the minimum delta is too small, then this loops forever. Add a sanity check. Allow reprogramming to fail 3 times, then print a warning and double the minimum delta value to make sure, that this does not happen again. Use the same function for both tick-oneshot and tick-broadcast code. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
144 lines
3.5 KiB
C
144 lines
3.5 KiB
C
/*
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* linux/kernel/time/tick-oneshot.c
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*
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* This file contains functions which manage high resolution tick
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* related events.
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*
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* Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
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* Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
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* Copyright(C) 2006-2007, Timesys Corp., Thomas Gleixner
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*
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* This code is licenced under the GPL version 2. For details see
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* kernel-base/COPYING.
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*/
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#include <linux/cpu.h>
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#include <linux/err.h>
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#include <linux/hrtimer.h>
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#include <linux/interrupt.h>
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#include <linux/percpu.h>
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#include <linux/profile.h>
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#include <linux/sched.h>
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#include <linux/tick.h>
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#include "tick-internal.h"
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/**
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* tick_program_event internal worker function
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*/
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int tick_dev_program_event(struct clock_event_device *dev, ktime_t expires,
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int force)
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{
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ktime_t now = ktime_get();
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int i;
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for (i = 0;;) {
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int ret = clockevents_program_event(dev, expires, now);
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if (!ret || !force)
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return ret;
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/*
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* We tried 2 times to program the device with the given
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* min_delta_ns. If that's not working then we double it
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* and emit a warning.
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*/
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if (++i > 2) {
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printk(KERN_WARNING "CE: __tick_program_event of %s is "
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"stuck %llx %llx\n", dev->name ? dev->name : "?",
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now.tv64, expires.tv64);
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printk(KERN_WARNING
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"CE: increasing min_delta_ns %ld to %ld nsec\n",
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dev->min_delta_ns, dev->min_delta_ns << 1);
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WARN_ON(1);
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/* Double the min. delta and try again */
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if (!dev->min_delta_ns)
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dev->min_delta_ns = 5000;
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else
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dev->min_delta_ns <<= 1;
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i = 0;
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}
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now = ktime_get();
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expires = ktime_add_ns(now, dev->min_delta_ns);
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}
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}
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/**
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* tick_program_event
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*/
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int tick_program_event(ktime_t expires, int force)
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{
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struct clock_event_device *dev = __get_cpu_var(tick_cpu_device).evtdev;
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return tick_dev_program_event(dev, expires, force);
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}
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/**
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* tick_resume_onshot - resume oneshot mode
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*/
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void tick_resume_oneshot(void)
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{
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struct tick_device *td = &__get_cpu_var(tick_cpu_device);
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struct clock_event_device *dev = td->evtdev;
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clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);
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tick_program_event(ktime_get(), 1);
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}
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/**
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* tick_setup_oneshot - setup the event device for oneshot mode (hres or nohz)
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*/
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void tick_setup_oneshot(struct clock_event_device *newdev,
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void (*handler)(struct clock_event_device *),
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ktime_t next_event)
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{
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newdev->event_handler = handler;
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clockevents_set_mode(newdev, CLOCK_EVT_MODE_ONESHOT);
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tick_dev_program_event(newdev, next_event, 1);
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}
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/**
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* tick_switch_to_oneshot - switch to oneshot mode
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*/
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int tick_switch_to_oneshot(void (*handler)(struct clock_event_device *))
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{
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struct tick_device *td = &__get_cpu_var(tick_cpu_device);
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struct clock_event_device *dev = td->evtdev;
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if (!dev || !(dev->features & CLOCK_EVT_FEAT_ONESHOT) ||
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!tick_device_is_functional(dev)) {
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printk(KERN_INFO "Clockevents: "
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"could not switch to one-shot mode:");
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if (!dev) {
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printk(" no tick device\n");
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} else {
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if (!tick_device_is_functional(dev))
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printk(" %s is not functional.\n", dev->name);
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else
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printk(" %s does not support one-shot mode.\n",
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dev->name);
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}
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return -EINVAL;
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}
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td->mode = TICKDEV_MODE_ONESHOT;
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dev->event_handler = handler;
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clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);
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tick_broadcast_switch_to_oneshot();
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return 0;
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}
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#ifdef CONFIG_HIGH_RES_TIMERS
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/**
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* tick_init_highres - switch to high resolution mode
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*
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* Called with interrupts disabled.
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*/
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int tick_init_highres(void)
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{
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return tick_switch_to_oneshot(hrtimer_interrupt);
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}
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#endif
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