Some timer backend doesn't particularly like (re)start / stop calls
from its interrupt handler. For example, hrtimer can't stop properly
with sync, and we still seem to have some open race.
This patch introduced a new flag, SNDRV_TIMER_HW_RET_CTRL, so that the
timer backend can specify whether snd_timer_interrupt() should call hw
start() and hw.stop() callbacks or not. If the new flag is set,
snd_timer_interrupt() won't call hw.start() and hw.stop() callbacks
but return SNDRV_TIMER_RET_START and SNDRV_TIMER_RET_STOP,
respectively.
The actual usage of this flag will be done in the later patch,
starting from hrtimer.
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
---
include/sound/timer.h | 12 +++++++++++-
sound/core/timer.c | 24 ++++++++++++++++++------
2 files changed, 29 insertions(+), 7 deletions(-)
diff --git a/include/sound/timer.h b/include/sound/timer.h
index c4d76ff056c6..6ca6ed4169da 100644
--- a/include/sound/timer.h
+++ b/include/sound/timer.h
@@ -37,6 +37,7 @@
#define SNDRV_TIMER_HW_SLAVE 0x00000004 /* only slave timer (variable resolution) */
#define SNDRV_TIMER_HW_FIRST 0x00000008 /* first tick can be incomplete */
#define SNDRV_TIMER_HW_TASKLET 0x00000010 /* timer is called from tasklet */
+#define SNDRV_TIMER_HW_RET_CTRL 0x00000020 /* don't start/stop at irq handler */
#define SNDRV_TIMER_IFLG_SLAVE 0x00000001
#define SNDRV_TIMER_IFLG_RUNNING 0x00000002
@@ -50,6 +51,15 @@
#define SNDRV_TIMER_FLG_CHANGE 0x00000001
#define SNDRV_TIMER_FLG_RESCHED 0x00000002 /* need reschedule */
+/* return value from snd_timer_interrupt();
+ * START and STOP are returned only when SNDRV_TIMER_HW_RET_CTRL is set
+ */
+enum {
+ SNDRV_TIMER_RET_NONE = 0,
+ SNDRV_TIMER_RET_START = 1,
+ SNDRV_TIMER_RET_STOP = 2,
+};
+
struct snd_timer;
struct snd_timer_hardware {
@@ -139,6 +149,6 @@ int snd_timer_stop(struct snd_timer_instance *timeri);
int snd_timer_continue(struct snd_timer_instance *timeri);
int snd_timer_pause(struct snd_timer_instance *timeri);
-void snd_timer_interrupt(struct snd_timer *timer, unsigned long ticks_left);
+int snd_timer_interrupt(struct snd_timer *timer, unsigned long ticks_left);
#endif /* __SOUND_TIMER_H */
diff --git a/sound/core/timer.c b/sound/core/timer.c
index 6469bedda2f3..c653c409d74d 100644
--- a/sound/core/timer.c
+++ b/sound/core/timer.c
@@ -683,19 +683,20 @@ static void snd_timer_tasklet(unsigned long arg)
* ticks_left is usually equal to timer->sticks.
*
*/
-void snd_timer_interrupt(struct snd_timer * timer, unsigned long ticks_left)
+int snd_timer_interrupt(struct snd_timer *timer, unsigned long ticks_left)
{
struct snd_timer_instance *ti, *ts, *tmp;
unsigned long resolution, ticks;
struct list_head *p, *ack_list_head;
unsigned long flags;
int use_tasklet = 0;
+ int ret = 0;
if (timer == NULL)
- return;
+ return -ENODEV;
if (timer->card && timer->card->shutdown)
- return;
+ return -ENODEV;
spin_lock_irqsave(&timer->lock, flags);
@@ -747,17 +748,26 @@ void snd_timer_interrupt(struct snd_timer * timer, unsigned long ticks_left)
snd_timer_reschedule(timer, timer->sticks);
if (timer->running) {
if (timer->hw.flags & SNDRV_TIMER_HW_STOP) {
- timer->hw.stop(timer);
+ if (timer->hw.flags & SNDRV_TIMER_HW_RET_CTRL)
+ ret = SNDRV_TIMER_RET_STOP;
+ else
+ timer->hw.stop(timer);
timer->flags |= SNDRV_TIMER_FLG_CHANGE;
}
if (!(timer->hw.flags & SNDRV_TIMER_HW_AUTO) ||
(timer->flags & SNDRV_TIMER_FLG_CHANGE)) {
/* restart timer */
timer->flags &= ~SNDRV_TIMER_FLG_CHANGE;
- timer->hw.start(timer);
+ if (timer->hw.flags & SNDRV_TIMER_HW_RET_CTRL)
+ ret = SNDRV_TIMER_RET_START;
+ else
+ timer->hw.start(timer);
}
} else {
- timer->hw.stop(timer);
+ if (timer->hw.flags & SNDRV_TIMER_HW_RET_CTRL)
+ ret = SNDRV_TIMER_RET_STOP;
+ else
+ timer->hw.stop(timer);
}
/* now process all fast callbacks */
@@ -785,6 +795,8 @@ void snd_timer_interrupt(struct snd_timer * timer, unsigned long ticks_left)
if (use_tasklet)
tasklet_schedule(&timer->task_queue);
+
+ return ret;
}
/*
--
2.8.1
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