Any suggestion for this patch?
On Mon, 2015-09-14 at 14:51 +0800, Koro Chen wrote:
In capture, there is chance that hw_ptr reported at IRQ is a little smaller than period_size due to internal AFE buffer. In the case of ping-pong buffer:
|xxxxxxxxxxxxxxxxxxxxxxxxxxxx--|-----------------------------| hw_ptr < period_size
This available buffer will not be read since its size is smaller than avail_min (which is period_size by default), and read thread continues to sleep. If the next hw_ptr is just a little larger than buffer_size, overrun occurs. One more period can hold the possible unread buffer.
Signed-off-by: Koro Chen koro.chen@mediatek.com
sound/soc/mediatek/mtk-afe-pcm.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+)
diff --git a/sound/soc/mediatek/mtk-afe-pcm.c b/sound/soc/mediatek/mtk-afe-pcm.c index d190fe0..f5baf3c 100644 --- a/sound/soc/mediatek/mtk-afe-pcm.c +++ b/sound/soc/mediatek/mtk-afe-pcm.c @@ -549,6 +549,23 @@ static int mtk_afe_dais_startup(struct snd_pcm_substream *substream, memif->substream = substream;
snd_soc_set_runtime_hwparams(substream, &mtk_afe_hardware);
- /*
* Capture cannot use ping-pong buffer since hw_ptr at IRQ may be* smaller than period_size due to AFE's internal buffer.* This easily leads to overrun when avail_min is period_size.* One more period can hold the possible unread buffer.*/- if (substream->stream == SNDRV_PCM_STREAM_CAPTURE) {
ret = snd_pcm_hw_constraint_minmax(runtime,SNDRV_PCM_HW_PARAM_PERIODS,3,mtk_afe_hardware.periods_max);if (ret < 0) {dev_err(afe->dev, "hw_constraint_minmax failed\n");return ret;}- } ret = snd_pcm_hw_constraint_integer(runtime, SNDRV_PCM_HW_PARAM_PERIODS); if (ret < 0)