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* reset of kernel input buffer for /dev/dsp
@ 2010-11-27 12:33 Amit Nagal
  2010-11-29  8:00 ` Clemens Ladisch
  0 siblings, 1 reply; 6+ messages in thread
From: Amit Nagal @ 2010-11-27 12:33 UTC (permalink / raw)
  To: alsa-devel; +Cc: alsa-user, tiwai, Clemens Ladisch

Hi ,

i am doing usb audio streaming using usb audio class interface .

our application is OSS based , uses OSS calls to interact with linux
audio driver .

Our device is capture only device .

we want to flush  kernel input pcm buffer  without using close() system call .

does OSS supports in userspace any ioctl call which can flush kernel
pcm buffer at any time .

right now we have to close audio-fd  and open audio-fd  again .

how we can flush  kernel input pcm buffer  without using close system
call in based OSS application

regards
Amit Nagal

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: reset of kernel input buffer for /dev/dsp
  2010-11-27 12:33 reset of kernel input buffer for /dev/dsp Amit Nagal
@ 2010-11-29  8:00 ` Clemens Ladisch
  2010-11-29  8:40   ` Amit Nagal
  0 siblings, 1 reply; 6+ messages in thread
From: Clemens Ladisch @ 2010-11-29  8:00 UTC (permalink / raw)
  To: Amit Nagal; +Cc: alsa-user, tiwai, alsa-devel

Amit Nagal wrote:
> we want to flush  kernel input pcm buffer  without using close() system call .
> 
> does OSS supports in userspace any ioctl call which can flush kernel
> pcm buffer at any time .

SNDCTL_DSP_RESET


Regards,
Clemens

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: reset of kernel input buffer for /dev/dsp
  2010-11-29  8:00 ` Clemens Ladisch
@ 2010-11-29  8:40   ` Amit Nagal
  2010-11-29  8:58     ` Takashi Iwai
  0 siblings, 1 reply; 6+ messages in thread
From: Amit Nagal @ 2010-11-29  8:40 UTC (permalink / raw)
  To: Clemens Ladisch; +Cc: alsa-user, tiwai, alsa-devel

Hi ,

Thanx for the reply .

we tried SNDCTL_DSP_RESET , but it is not flushing  the kernel pcm
buffer for us  .

any other method which we can use ?

also please lets us the function available with alsa - lib which
serves the purpose of flushing
the kernel pcm buffer .

thanx & regards
amit nagal






On Mon, Nov 29, 2010 at 5:00 PM, Clemens Ladisch <clemens@ladisch.de> wrote:
> Amit Nagal wrote:
>> we want to flush  kernel input pcm buffer  without using close() system call .
>>
>> does OSS supports in userspace any ioctl call which can flush kernel
>> pcm buffer at any time .
>
> SNDCTL_DSP_RESET
>
>
> Regards,
> Clemens
>

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: reset of kernel input buffer for /dev/dsp
  2010-11-29  8:40   ` Amit Nagal
@ 2010-11-29  8:58     ` Takashi Iwai
  2010-11-30  2:51       ` Amit Nagal
  0 siblings, 1 reply; 6+ messages in thread
From: Takashi Iwai @ 2010-11-29  8:58 UTC (permalink / raw)
  To: Amit Nagal; +Cc: alsa-user, alsa-devel, Clemens Ladisch

At Mon, 29 Nov 2010 17:40:03 +0900,
Amit Nagal wrote:
> 
> Hi ,
> 
> Thanx for the reply .
> 
> we tried SNDCTL_DSP_RESET , but it is not flushing  the kernel pcm
> buffer for us  .

It should.  It abandons the pending data and resets to the initial
state before starting the stream.

But, it might be a bug in OSS emulation later.  It doesn't seem to
reset the internal buffer.  Try the patch below.

> any other method which we can use ?

> also please lets us the function available with alsa - lib which
> serves the purpose of flushing
> the kernel pcm buffer .

snd_pcm_drop() corresponds to it.


Takashi

---
diff --git a/sound/core/oss/pcm_oss.c b/sound/core/oss/pcm_oss.c
index 5c8c7df..a4411a3 100644
--- a/sound/core/oss/pcm_oss.c
+++ b/sound/core/oss/pcm_oss.c
@@ -1510,16 +1510,19 @@ static ssize_t snd_pcm_oss_read1(struct snd_pcm_substream *substream, char __use
 static int snd_pcm_oss_reset(struct snd_pcm_oss_file *pcm_oss_file)
 {
 	struct snd_pcm_substream *substream;
+	struct snd_pcm_runtime *runtime;
+	int i;
 
-	substream = pcm_oss_file->streams[SNDRV_PCM_STREAM_PLAYBACK];
-	if (substream != NULL) {
-		snd_pcm_kernel_ioctl(substream, SNDRV_PCM_IOCTL_DROP, NULL);
-		substream->runtime->oss.prepare = 1;
-	}
-	substream = pcm_oss_file->streams[SNDRV_PCM_STREAM_CAPTURE];
-	if (substream != NULL) {
+	for (i = 0; i < 2; i++) { 
+		substream = pcm_oss_file->streams[i];
+		if (!substream)
+			continue;
+		runtime = substream->runtine;
 		snd_pcm_kernel_ioctl(substream, SNDRV_PCM_IOCTL_DROP, NULL);
-		substream->runtime->oss.prepare = 1;
+		runtime->oss.prepare = 1;
+		runtime->oss.buffer_used = 0;
+		runtime->oss.prev_hw_ptr_period = 0;
+		runtime->oss.period_ptr = 0;
 	}
 	return 0;
 }

^ permalink raw reply related	[flat|nested] 6+ messages in thread
* Re: reset of kernel input buffer for /dev/dsp
  2010-11-29  8:58     ` Takashi Iwai
@ 2010-11-30  2:51       ` Amit Nagal
  2010-11-30  7:20         ` Takashi Iwai
  0 siblings, 1 reply; 6+ messages in thread
From: Amit Nagal @ 2010-11-30  2:51 UTC (permalink / raw)
  To: Takashi Iwai; +Cc: alsa-user, alsa-devel, Clemens Ladisch

Hi ,

Thanx for the patch . Application of this patch resolves kernel pcm
ring buffer flush problem .
Now SNDCTL_DSP_RESET works properly .


On a suggestive note  ,  as this bug is present in main stream kernel also ,
this patch should also be applied as well .

Thanx & Regards
Amit Nagal




On Mon, Nov 29, 2010 at 5:58 PM, Takashi Iwai <tiwai@suse.de> wrote:
> At Mon, 29 Nov 2010 17:40:03 +0900,
> Amit Nagal wrote:
>>
>> Hi ,
>>
>> Thanx for the reply .
>>
>> we tried SNDCTL_DSP_RESET , but it is not flushing  the kernel pcm
>> buffer for us  .
>
> It should.  It abandons the pending data and resets to the initial
> state before starting the stream.
>
> But, it might be a bug in OSS emulation later.  It doesn't seem to
> reset the internal buffer.  Try the patch below.
>
>> any other method which we can use ?
>
>> also please lets us the function available with alsa - lib which
>> serves the purpose of flushing
>> the kernel pcm buffer .
>
> snd_pcm_drop() corresponds to it.
>
>
> Takashi
>
> ---
> diff --git a/sound/core/oss/pcm_oss.c b/sound/core/oss/pcm_oss.c
> index 5c8c7df..a4411a3 100644
> --- a/sound/core/oss/pcm_oss.c
> +++ b/sound/core/oss/pcm_oss.c
> @@ -1510,16 +1510,19 @@ static ssize_t snd_pcm_oss_read1(struct snd_pcm_substream *substream, char __use
>  static int snd_pcm_oss_reset(struct snd_pcm_oss_file *pcm_oss_file)
>  {
>        struct snd_pcm_substream *substream;
> +       struct snd_pcm_runtime *runtime;
> +       int i;
>
> -       substream = pcm_oss_file->streams[SNDRV_PCM_STREAM_PLAYBACK];
> -       if (substream != NULL) {
> -               snd_pcm_kernel_ioctl(substream, SNDRV_PCM_IOCTL_DROP, NULL);
> -               substream->runtime->oss.prepare = 1;
> -       }
> -       substream = pcm_oss_file->streams[SNDRV_PCM_STREAM_CAPTURE];
> -       if (substream != NULL) {
> +       for (i = 0; i < 2; i++) {
> +               substream = pcm_oss_file->streams[i];
> +               if (!substream)
> +                       continue;
> +               runtime = substream->runtine;
>                snd_pcm_kernel_ioctl(substream, SNDRV_PCM_IOCTL_DROP, NULL);
> -               substream->runtime->oss.prepare = 1;
> +               runtime->oss.prepare = 1;
> +               runtime->oss.buffer_used = 0;
> +               runtime->oss.prev_hw_ptr_period = 0;
> +               runtime->oss.period_ptr = 0;
>        }
>        return 0;
>  }
>

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: reset of kernel input buffer for /dev/dsp
  2010-11-30  2:51       ` Amit Nagal
@ 2010-11-30  7:20         ` Takashi Iwai
  0 siblings, 0 replies; 6+ messages in thread
From: Takashi Iwai @ 2010-11-30  7:20 UTC (permalink / raw)
  To: Amit Nagal; +Cc: alsa-user, alsa-devel, Clemens Ladisch

At Tue, 30 Nov 2010 11:51:33 +0900,
Amit Nagal wrote:
> 
> Hi ,
> 
> Thanx for the patch . Application of this patch resolves kernel pcm
> ring buffer flush problem .
> Now SNDCTL_DSP_RESET works properly .
> 
> 
> On a suggestive note  ,  as this bug is present in main stream kernel also ,
> this patch should also be applied as well .

Thanks for testing.  Yes, I applied the patch now, and it'll be included
in the stable kernel as well.


Takashi

> 
> Thanx & Regards
> Amit Nagal
> 
> 
> 
> 
> On Mon, Nov 29, 2010 at 5:58 PM, Takashi Iwai <tiwai@suse.de> wrote:
> > At Mon, 29 Nov 2010 17:40:03 +0900,
> > Amit Nagal wrote:
> >>
> >> Hi ,
> >>
> >> Thanx for the reply .
> >>
> >> we tried SNDCTL_DSP_RESET , but it is not flushing  the kernel pcm
> >> buffer for us  .
> >
> > It should.  It abandons the pending data and resets to the initial
> > state before starting the stream.
> >
> > But, it might be a bug in OSS emulation later.  It doesn't seem to
> > reset the internal buffer.  Try the patch below.
> >
> >> any other method which we can use ?
> >
> >> also please lets us the function available with alsa - lib which
> >> serves the purpose of flushing
> >> the kernel pcm buffer .
> >
> > snd_pcm_drop() corresponds to it.
> >
> >
> > Takashi
> >
> > ---
> > diff --git a/sound/core/oss/pcm_oss.c b/sound/core/oss/pcm_oss.c
> > index 5c8c7df..a4411a3 100644
> > --- a/sound/core/oss/pcm_oss.c
> > +++ b/sound/core/oss/pcm_oss.c
> > @@ -1510,16 +1510,19 @@ static ssize_t snd_pcm_oss_read1(struct snd_pcm_substream *substream, char __use
> >  static int snd_pcm_oss_reset(struct snd_pcm_oss_file *pcm_oss_file)
> >  {
> >        struct snd_pcm_substream *substream;
> > +       struct snd_pcm_runtime *runtime;
> > +       int i;
> >
> > -       substream = pcm_oss_file->streams[SNDRV_PCM_STREAM_PLAYBACK];
> > -       if (substream != NULL) {
> > -               snd_pcm_kernel_ioctl(substream, SNDRV_PCM_IOCTL_DROP, NULL);
> > -               substream->runtime->oss.prepare = 1;
> > -       }
> > -       substream = pcm_oss_file->streams[SNDRV_PCM_STREAM_CAPTURE];
> > -       if (substream != NULL) {
> > +       for (i = 0; i < 2; i++) {
> > +               substream = pcm_oss_file->streams[i];
> > +               if (!substream)
> > +                       continue;
> > +               runtime = substream->runtine;
> >                snd_pcm_kernel_ioctl(substream, SNDRV_PCM_IOCTL_DROP, NULL);
> > -               substream->runtime->oss.prepare = 1;
> > +               runtime->oss.prepare = 1;
> > +               runtime->oss.buffer_used = 0;
> > +               runtime->oss.prev_hw_ptr_period = 0;
> > +               runtime->oss.period_ptr = 0;
> >        }
> >        return 0;
> >  }
> >
> 
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^ permalink raw reply	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2010-11-30  7:20 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2010-11-27 12:33 reset of kernel input buffer for /dev/dsp Amit Nagal
2010-11-29  8:00 ` Clemens Ladisch
2010-11-29  8:40   ` Amit Nagal
2010-11-29  8:58     ` Takashi Iwai
2010-11-30  2:51       ` Amit Nagal
2010-11-30  7:20         ` Takashi Iwai

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