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ALSA: seq: Process queue tempo/ppq change in a shot 

The SNDRV_SEQ_IOCTL_SET_QUEUE_TEMPO ioctl sets the tempo and the ppq
in a single call, while the current implementation updates each value
one by one.  This is a bit racy, and also suboptimal from the
performance POV, as each call does re-acquire the lock and invokes
the update of ALSA timer resolution.

This patch reorganizes the code slightly so that we change both the
tempo and the ppq in a shot.  The skew value can be put into the same
lock, but this is rather a rarely used feature and completely
independent from the temp/ppq (it's evaluated only in the interrupt),
so it's left as it was.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Iwai 2018-01-15 16:48:36 +01:00
parent 4ea5553a51
commit 671ec859e5
3 changed files with 10 additions and 9 deletions
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4
sound/core/seq/seq_queue.c
View File

@ -497,9 +497,7 @@ int snd_seq_queue_timer_set_tempo(int queueid, int client,
return -EPERM; return -EPERM;
} }
result = snd_seq_timer_set_tempo(q->timer, info->tempo); result = snd_seq_timer_set_tempo_ppq(q->timer, info->tempo, info->ppq);
if (result >= 0)
result = snd_seq_timer_set_ppq(q->timer, info->ppq);
if (result >= 0 && info->skew_base > 0) if (result >= 0 && info->skew_base > 0)
result = snd_seq_timer_set_skew(q->timer, info->skew_value, result = snd_seq_timer_set_skew(q->timer, info->skew_value,
info->skew_base); info->skew_base);

13
sound/core/seq/seq_timer.c
View File

@ -191,14 +191,15 @@ int snd_seq_timer_set_tempo(struct snd_seq_timer * tmr, int tempo)
return 0; return 0;
} }
/* set current ppq */ /* set current tempo and ppq in a shot */
int snd_seq_timer_set_ppq(struct snd_seq_timer * tmr, int ppq) int snd_seq_timer_set_tempo_ppq(struct snd_seq_timer *tmr, int tempo, int ppq)
{ {
int changed;
unsigned long flags; unsigned long flags;
if (snd_BUG_ON(!tmr)) if (snd_BUG_ON(!tmr))
return -EINVAL; return -EINVAL;
if (ppq <= 0) if (tempo <= 0 || ppq <= 0)
return -EINVAL; return -EINVAL;
spin_lock_irqsave(&tmr->lock, flags); spin_lock_irqsave(&tmr->lock, flags);
if (tmr->running && (ppq != tmr->ppq)) { if (tmr->running && (ppq != tmr->ppq)) {
@ -208,9 +209,11 @@ int snd_seq_timer_set_ppq(struct snd_seq_timer * tmr, int ppq)
pr_debug("ALSA: seq: cannot change ppq of a running timer\n"); pr_debug("ALSA: seq: cannot change ppq of a running timer\n");
return -EBUSY; return -EBUSY;
} }
changed = (tempo != tmr->tempo) || (ppq != tmr->ppq);
tmr->tempo = tempo;
tmr->ppq = ppq; tmr->ppq = ppq;
snd_seq_timer_set_tick_resolution(tmr); if (changed)
snd_seq_timer_set_tick_resolution(tmr);
spin_unlock_irqrestore(&tmr->lock, flags); spin_unlock_irqrestore(&tmr->lock, flags);
return 0; return 0;
} }

2
sound/core/seq/seq_timer.h
View File

@ -131,7 +131,7 @@ int snd_seq_timer_stop(struct snd_seq_timer *tmr);
int snd_seq_timer_start(struct snd_seq_timer *tmr); int snd_seq_timer_start(struct snd_seq_timer *tmr);
int snd_seq_timer_continue(struct snd_seq_timer *tmr); int snd_seq_timer_continue(struct snd_seq_timer *tmr);
int snd_seq_timer_set_tempo(struct snd_seq_timer *tmr, int tempo); int snd_seq_timer_set_tempo(struct snd_seq_timer *tmr, int tempo);
int snd_seq_timer_set_ppq(struct snd_seq_timer *tmr, int ppq); int snd_seq_timer_set_tempo_ppq(struct snd_seq_timer *tmr, int tempo, int ppq);
int snd_seq_timer_set_position_tick(struct snd_seq_timer *tmr, snd_seq_tick_time_t position); int snd_seq_timer_set_position_tick(struct snd_seq_timer *tmr, snd_seq_tick_time_t position);
int snd_seq_timer_set_position_time(struct snd_seq_timer *tmr, snd_seq_real_time_t position); int snd_seq_timer_set_position_time(struct snd_seq_timer *tmr, snd_seq_real_time_t position);
int snd_seq_timer_set_skew(struct snd_seq_timer *tmr, unsigned int skew, unsigned int base); int snd_seq_timer_set_skew(struct snd_seq_timer *tmr, unsigned int skew, unsigned int base);