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[ALSA] seq-timer: restrict timer frequencies

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Modules: ALSA sequencer

When no default timer frequency has been set, initialize_timer() just
uses the maximum frequency supported by the timer, which is ridiculously
high on 96 kHz timers.

This patch introduces a default frequency of 1000 Hz for this case, and
makes sure that a frequency set by the user isn't too high.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
This commit is contained in:
Clemens Ladisch 2005-10-19 14:38:30 +02:00 committed by Jaroslav Kysela
parent 051b516533
commit 87ef7779be
1 changed files with 17 additions and 3 deletions
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20
sound/core/seq/seq_timer.c
View file

@ -34,6 +34,11 @@ extern int seq_default_timer_device;
extern int seq_default_timer_subdevice;
extern int seq_default_timer_resolution;
/* allowed sequencer timer frequencies, in Hz */
#define MIN_FREQUENCY 10
#define MAX_FREQUENCY 6250
#define DEFAULT_FREQUENCY 1000
#define SKEW_BASE 0x10000 /* 16bit shift */
static void snd_seq_timer_set_tick_resolution(seq_timer_tick_t *tick,
@ -325,17 +330,26 @@ int snd_seq_timer_stop(seq_timer_t * tmr)
static int initialize_timer(seq_timer_t *tmr)
{
snd_timer_t *t;
unsigned long freq;
t = tmr->timeri->timer;
snd_assert(t, return -EINVAL);
freq = tmr->preferred_resolution;
if (!freq)
freq = DEFAULT_FREQUENCY;
else if (freq < MIN_FREQUENCY)
freq = MIN_FREQUENCY;
else if (freq > MAX_FREQUENCY)
freq = MAX_FREQUENCY;
tmr->ticks = 1;
if (tmr->preferred_resolution &&
! (t->hw.flags & SNDRV_TIMER_HW_SLAVE)) {
if (!(t->hw.flags & SNDRV_TIMER_HW_SLAVE)) {
unsigned long r = t->hw.resolution;
if (! r && t->hw.c_resolution)
r = t->hw.c_resolution(t);
if (r) {
tmr->ticks = (unsigned int)(1000000000uL / (r * tmr->preferred_resolution));
tmr->ticks = (unsigned int)(1000000000uL / (r * freq));
if (! tmr->ticks)
tmr->ticks = 1;
}