2243c4d072
Commit bb758e9637 removed snd_hrtimer_callback() from the hardware
interrupt handler, thus moving it into a tasklet, but did not tell the
ALSA timer framework about this, so the timer handling would now be done
in the ALSA timer tasklet scheduled from another tasklet.
To fix this, add the flag to tell the ALSA timer framework that the
timer handler is already being invoked in a tasklet.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
167 lines
4.1 KiB
C
167 lines
4.1 KiB
C
/*
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* ALSA timer back-end using hrtimer
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* Copyright (C) 2008 Takashi Iwai
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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*/
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#include <linux/init.h>
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#include <linux/slab.h>
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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/hrtimer.h>
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#include <sound/core.h>
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#include <sound/timer.h>
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MODULE_AUTHOR("Takashi Iwai <tiwai@suse.de>");
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MODULE_DESCRIPTION("ALSA hrtimer backend");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("snd-timer-" __stringify(SNDRV_TIMER_GLOBAL_HRTIMER));
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#define NANO_SEC 1000000000UL /* 10^9 in sec */
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static unsigned int resolution;
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struct snd_hrtimer {
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struct snd_timer *timer;
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struct hrtimer hrt;
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atomic_t running;
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};
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static enum hrtimer_restart snd_hrtimer_callback(struct hrtimer *hrt)
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{
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struct snd_hrtimer *stime = container_of(hrt, struct snd_hrtimer, hrt);
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struct snd_timer *t = stime->timer;
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unsigned long oruns;
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if (!atomic_read(&stime->running))
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return HRTIMER_NORESTART;
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oruns = hrtimer_forward_now(hrt, ns_to_ktime(t->sticks * resolution));
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snd_timer_interrupt(stime->timer, t->sticks * oruns);
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if (!atomic_read(&stime->running))
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return HRTIMER_NORESTART;
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return HRTIMER_RESTART;
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}
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static int snd_hrtimer_open(struct snd_timer *t)
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{
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struct snd_hrtimer *stime;
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stime = kmalloc(sizeof(*stime), GFP_KERNEL);
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if (!stime)
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return -ENOMEM;
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hrtimer_init(&stime->hrt, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
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stime->timer = t;
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stime->hrt.function = snd_hrtimer_callback;
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atomic_set(&stime->running, 0);
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t->private_data = stime;
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return 0;
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}
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static int snd_hrtimer_close(struct snd_timer *t)
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{
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struct snd_hrtimer *stime = t->private_data;
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if (stime) {
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hrtimer_cancel(&stime->hrt);
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kfree(stime);
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t->private_data = NULL;
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}
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return 0;
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}
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static int snd_hrtimer_start(struct snd_timer *t)
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{
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struct snd_hrtimer *stime = t->private_data;
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atomic_set(&stime->running, 0);
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hrtimer_cancel(&stime->hrt);
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hrtimer_start(&stime->hrt, ns_to_ktime(t->sticks * resolution),
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HRTIMER_MODE_REL);
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atomic_set(&stime->running, 1);
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return 0;
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}
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static int snd_hrtimer_stop(struct snd_timer *t)
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{
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struct snd_hrtimer *stime = t->private_data;
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atomic_set(&stime->running, 0);
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return 0;
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}
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static struct snd_timer_hardware hrtimer_hw = {
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.flags = SNDRV_TIMER_HW_AUTO | SNDRV_TIMER_HW_TASKLET,
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.open = snd_hrtimer_open,
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.close = snd_hrtimer_close,
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.start = snd_hrtimer_start,
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.stop = snd_hrtimer_stop,
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};
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/*
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* entry functions
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*/
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static struct snd_timer *mytimer;
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static int __init snd_hrtimer_init(void)
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{
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struct snd_timer *timer;
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struct timespec tp;
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int err;
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hrtimer_get_res(CLOCK_MONOTONIC, &tp);
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if (tp.tv_sec > 0 || !tp.tv_nsec) {
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snd_printk(KERN_ERR
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"snd-hrtimer: Invalid resolution %u.%09u",
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(unsigned)tp.tv_sec, (unsigned)tp.tv_nsec);
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return -EINVAL;
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}
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resolution = tp.tv_nsec;
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/* Create a new timer and set up the fields */
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err = snd_timer_global_new("hrtimer", SNDRV_TIMER_GLOBAL_HRTIMER,
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&timer);
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if (err < 0)
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return err;
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timer->module = THIS_MODULE;
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strcpy(timer->name, "HR timer");
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timer->hw = hrtimer_hw;
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timer->hw.resolution = resolution;
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timer->hw.ticks = NANO_SEC / resolution;
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err = snd_timer_global_register(timer);
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if (err < 0) {
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snd_timer_global_free(timer);
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return err;
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}
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mytimer = timer; /* remember this */
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return 0;
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}
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static void __exit snd_hrtimer_exit(void)
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{
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if (mytimer) {
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snd_timer_global_free(mytimer);
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mytimer = NULL;
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}
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}
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module_init(snd_hrtimer_init);
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module_exit(snd_hrtimer_exit);
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