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, ...
An example of such situation is snd_pcm_lib_read1/write1 consuming some space of the period and going to sleep from wait_for_avail_min upon syncing with the DMA pointer. Clearly just the remainder of period size is needed, but wake_up is called only after _two_ periodic interrupts from that point.
In that case, the original behavior is correct.
thanks,
Takashi
Signed-off-by: Jassi Brar jassi.brar@samsung.com
sound/core/pcm_lib.c | 10 ++++++++-- 1 files changed, 8 insertions(+), 2 deletions(-)
diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c index 30f4108..ee2d7b9 100644 --- a/sound/core/pcm_lib.c +++ b/sound/core/pcm_lib.c @@ -189,7 +189,7 @@ snd_pcm_update_hw_ptr_pos(struct snd_pcm_substream *substream, static int snd_pcm_update_hw_ptr_post(struct snd_pcm_substream *substream, struct snd_pcm_runtime *runtime) {
- snd_pcm_uframes_t avail;
snd_pcm_uframes_t avail, prd_short;
if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) avail = snd_pcm_playback_avail(runtime);
@@ -208,8 +208,14 @@ static int snd_pcm_update_hw_ptr_post(struct snd_pcm_substream *substream, return -EPIPE; } }
- if (avail >= runtime->control->avail_min)
- prd_short = runtime->period_size
- runtime->status->hw_ptr % runtime->period_size;- if (avail >= runtime->control->avail_min
|| avail >= prd_short)- return 0;
}
-- 1.6.2.5