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; }