| Message ID | 1431527943-64178-1-git-send-email-koro.chen@mediatek.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 13a988396cab68e6c6afd33e461a9e52ce23ff63 |
| Headers | show |
At Wed, 13 May 2015 22:39:03 +0800, Koro Chen wrote: > > Currently in snd_pcm_update_hw_ptr0 during interrupt, > we consider there were double acknowledged interrupts when: > 1. HW reported pointer is smaller than expected, and > 2. Time from last update time (hdelta) is over half a buffer time. > > However, when HW reported pointer is only a few bytes smaller than > expected, and when hdelta is just a little larger than half a buffer time > (e.g. ping-pong buffer), it wrongly treats this IRQ as double acknowledged. > > The condition #2 uses jiffies, but jiffies is not high resolution > since it is integer. We should consider jiffies inaccuracy. > > Signed-off-by: Koro Chen <koro.chen@mediatek.com> The condition looks too strict, indeed. I applied the patch as is now. BTW, the similar check is already present for the free-wheeling case. I'm going to clean up the code a bit for using the common code. thanks, Takashi > --- > sound/core/pcm_lib.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c > index ac6b33f..7d45645 100644 > --- a/sound/core/pcm_lib.c > +++ b/sound/core/pcm_lib.c > @@ -339,7 +339,7 @@ static int snd_pcm_update_hw_ptr0(struct snd_pcm_substream *substream, > if (delta > new_hw_ptr) { > /* check for double acknowledged interrupts */ > hdelta = curr_jiffies - runtime->hw_ptr_jiffies; > - if (hdelta > runtime->hw_ptr_buffer_jiffies/2) { > + if (hdelta > runtime->hw_ptr_buffer_jiffies/2 + 1) { > hw_base += runtime->buffer_size; > if (hw_base >= runtime->boundary) { > hw_base = 0; > -- > 1.8.1.1.dirty >
diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c index ac6b33f..7d45645 100644 --- a/sound/core/pcm_lib.c +++ b/sound/core/pcm_lib.c @@ -339,7 +339,7 @@ static int snd_pcm_update_hw_ptr0(struct snd_pcm_substream *substream, if (delta > new_hw_ptr) { /* check for double acknowledged interrupts */ hdelta = curr_jiffies - runtime->hw_ptr_jiffies; - if (hdelta > runtime->hw_ptr_buffer_jiffies/2) { + if (hdelta > runtime->hw_ptr_buffer_jiffies/2 + 1) { hw_base += runtime->buffer_size; if (hw_base >= runtime->boundary) { hw_base = 0;
Currently in snd_pcm_update_hw_ptr0 during interrupt, we consider there were double acknowledged interrupts when: 1. HW reported pointer is smaller than expected, and 2. Time from last update time (hdelta) is over half a buffer time. However, when HW reported pointer is only a few bytes smaller than expected, and when hdelta is just a little larger than half a buffer time (e.g. ping-pong buffer), it wrongly treats this IRQ as double acknowledged. The condition #2 uses jiffies, but jiffies is not high resolution since it is integer. We should consider jiffies inaccuracy. Signed-off-by: Koro Chen <koro.chen@mediatek.com> --- sound/core/pcm_lib.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)