On Fri, 30 Dec 2016 07:29:27 +0100,
sutar.mounesh@xxxxxxxxx wrote:
>
> From: mahendran.k <mahendran.kuppusamy@xxxxxxxxxxxx>
>
> For long time test case, the slave_hw_ptr will exceed the boundary
> and wraparound the slave_hw_ptr. This slave boundary wraparound will
> cause the rate->hw_ptr to wraparound irrespective of the rate->boundary
> availability and due to that the available size goes wrong.
>
> Hence, To get the correct available size,
> - Its necessary to increment the rate->hw_ptr upto the rate->boundary
> and then wraparound the rate->hw_ptr.
> - While handling fraction part of slave period, rounded value will be
> introduced by input_frames(). To eliminate rounding issue on rate->hw_ptr,
> subtract last rounded value from rate->hw_ptr and add new rounded value
> of present slave_hw_ptr fraction part to rate->hw_ptr.
>
> Signed-off-by: mahendran.k <mahendran.kuppusamy@xxxxxxxxxxxx>
> Signed-off-by: Mounesh Sutar <mounesh_sutar@xxxxxxxxxx>
Thanks, it's been a long-standing issue, indeed.
I applied this one (again) with a slight coding style fix now.
But...
> diff --git a/src/pcm/pcm_rate.c b/src/pcm/pcm_rate.c
> index 1f830dd..5bee77c 100644
> --- a/src/pcm/pcm_rate.c
> +++ b/src/pcm/pcm_rate.c
> @@ -50,7 +50,7 @@ typedef struct _snd_pcm_rate snd_pcm_rate_t;
>
> struct _snd_pcm_rate {
> snd_pcm_generic_t gen;
> - snd_pcm_uframes_t appl_ptr, hw_ptr;
> + snd_pcm_uframes_t appl_ptr, hw_ptr, last_slave_hw_ptr;
> snd_pcm_uframes_t last_commit_ptr;
> snd_pcm_uframes_t orig_avail_min;
> snd_pcm_sw_params_t sw_params;
> @@ -563,14 +563,28 @@ static inline void snd_pcm_rate_sync_hwptr0(snd_pcm_t *pcm, snd_pcm_uframes_t sl
> {
> snd_pcm_rate_t *rate = pcm->private_data;
>
> + snd_pcm_sframes_t slave_hw_ptr_diff = slave_hw_ptr - rate->last_slave_hw_ptr;
> + snd_pcm_sframes_t last_slave_hw_ptr_frac;
> +
> if (pcm->stream != SND_PCM_STREAM_PLAYBACK)
> return;
> - /* FIXME: boundary overlap of slave hw_ptr isn't evaluated here!
> - * e.g. if slave rate is small...
> - */
> - rate->hw_ptr =
> - (slave_hw_ptr / rate->gen.slave->period_size) * pcm->period_size +
> - rate->ops.input_frames(rate->obj, slave_hw_ptr % rate->gen.slave->period_size);
> +
> + if (slave_hw_ptr_diff < 0)
> + slave_hw_ptr_diff += rate->gen.slave->boundary; /* slave boundary wraparound */
> + else if (slave_hw_ptr_diff == 0)
> + return;
> + last_slave_hw_ptr_frac = rate->last_slave_hw_ptr % rate->gen.slave->period_size;
> + /* While handling fraction part fo slave period, rounded value will be introduced by input_frames().
> + * To eliminate rounding issue on rate->hw_ptr, subtract last rounded value from rate->hw_ptr and
> + * add new rounded value of present slave_hw_ptr fraction part to rate->hw_ptr. Hence,
> + * rate->hw_ptr += [ (no. of updated slave periods * pcm rate period size) -
> + * fractional part of last_slave_hw_ptr rounded value +
> + * fractional part of updated slave hw ptr's rounded value ] */
> + rate->hw_ptr += (
> + (((last_slave_hw_ptr_frac + slave_hw_ptr_diff) / rate->gen.slave->period_size) * pcm->period_size) -
> + rate->ops.input_frames(rate->obj, last_slave_hw_ptr_frac) +
> + rate->ops.input_frames(rate->obj, (last_slave_hw_ptr_frac + slave_hw_ptr_diff) % rate->gen.slave->period_size));
> + rate->last_slave_hw_ptr = slave_hw_ptr;
.... this ended up with a substantial increase of computation.
Can we optimize, e.g. doing this conditionally only for the
overwrapping case?
thanks,
Takashi
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