On Mon, Dec 21, 2009 at 8:28 PM, Takashi Iwai tiwai@suse.de wrote:
At Thu, 17 Dec 2009 17:21:28 +0900, jassi brar wrote:
On Thu, Dec 17, 2009 at 4:43 PM, Takashi Iwai tiwai@suse.de wrote:
At Thu, 17 Dec 2009 16:31:08 +0900, jassi brar wrote:
On Thu, Dec 17, 2009 at 4:02 PM, Takashi Iwai tiwai@suse.de wrote:
At Thu, 17 Dec 2009 15:00:02 +0900, jassisinghbrar@gmail.com wrote:
From: Jassi Brar jassi.brar@samsung.com
The check for at least 'avail_min' available data before calling wake_up doesn't always hold good as it does not guarantee callbacks at each periodic interrupt.
Well, avail_min can be greater than period_size. And, avail_min won't be less than period size.
For example, when avail_min = 2.5 x period_size, the driver wakes up in periods like 3, 2, 3, 2, ...
correct, but if we ensure wake_up's after each period and let the 'sleepers' track if the data available is enough or not, we will have more fine grained control. The point is:- Waking up _after_ avail_min is working, but does waking up before avail_min(but at period boundary) break the system?
PulseAudio may complain :)
I meant effects on ALSA state-machine within the kernel.
From what i have seen, every use of sleep is just to kill some time,
i.e, wake_up is not taken as indication of completion of the purpose.
It's used also for poll.
Meanwhile, we may change snd_pcm_*_poll() function itself, too...
How about employing a new snd_pcm_runtime member (say, need_min) which denote the _exact_ minimum amount of data needed to serve purpose of last sleep ?
Quick idea of what i mean, follows. If you like it, i will resend the patches again Thanks.
diff --git a/include/sound/pcm.h b/include/sound/pcm.h index de6d981..b5a9e81 100644 --- a/include/sound/pcm.h +++ b/include/sound/pcm.h @@ -267,6 +267,7 @@ struct snd_pcm_runtime { struct snd_pcm_substream *trigger_master; struct timespec trigger_tstamp; /* trigger timestamp */ int overrange; + snd_pcm_uframes_t need_min; /* exact minimum needed before wakeup */ snd_pcm_uframes_t avail_max; snd_pcm_uframes_t hw_ptr_base; /* Position at buffer restart */ snd_pcm_uframes_t hw_ptr_interrupt; /* Position at interrupt time */ diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c index 30f4108..a689add 100644 --- a/sound/core/pcm_lib.c +++ b/sound/core/pcm_lib.c @@ -208,7 +208,7 @@ static int snd_pcm_update_hw_ptr_post(struct snd_pcm_substream *substream, return -EPIPE; } } - if (avail >= runtime->control->avail_min) + if (avail >= runtime->need_min) wake_up(&runtime->sleep); return 0; } @@ -1681,6 +1681,7 @@ static int wait_for_avail_min(struct snd_pcm_substream *substream, break; } set_current_state(TASK_INTERRUPTIBLE); + runtime->need_min = *availp; snd_pcm_stream_unlock_irq(substream); tout = schedule_timeout(msecs_to_jiffies(10000)); snd_pcm_stream_lock_irq(substream); @@ -1788,6 +1789,7 @@ static snd_pcm_sframes_t snd_pcm_lib_write1(struct snd_pcm_substream *substream, err = -EAGAIN; goto _end_unlock; } + avail = size; err = wait_for_avail_min(substream, &avail); if (err < 0) goto _end_unlock; @@ -2010,6 +2012,7 @@ static snd_pcm_sframes_t snd_pcm_lib_read1(struct snd_pcm_substream *substream, err = -EAGAIN; goto _end_unlock; } + avail = size; err = wait_for_avail_min(substream, &avail); if (err < 0) goto _end_unlock; diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c index ab73edf..6e5dfa2 100644 --- a/sound/core/pcm_native.c +++ b/sound/core/pcm_native.c @@ -2892,6 +2892,10 @@ static unsigned int snd_pcm_playback_poll(struct file *file, poll_table * wait) return -ENXIO; runtime = substream->runtime;
+ snd_pcm_stream_lock_irq(substream); + runtime->need_min = runtime->control->avail_min; + snd_pcm_stream_unlock_irq(substream); + poll_wait(file, &runtime->sleep, wait);
snd_pcm_stream_lock_irq(substream); @@ -2931,6 +2935,10 @@ static unsigned int snd_pcm_capture_poll(struct file *file, poll_table * wait) return -ENXIO; runtime = substream->runtime;
+ snd_pcm_stream_lock_irq(substream); + runtime->need_min = runtime->control->avail_min; + snd_pcm_stream_unlock_irq(substream); + poll_wait(file, &runtime->sleep, wait);
snd_pcm_stream_lock_irq(substream);