Hi,
On 6/4/24 1:01 PM, Jai Luthra wrote:
> The minimum period size was enforced to 64 as older devices integrating
> McASP with EDMA used an internal FIFO of 64 samples.
>
> With UDMA based platforms this internal McASP FIFO is optional, as the
> DMA engine internally does some buffering which is already accounted for
> when registering the platform. So we should read the actual FIFO
> configuration (txnumevt/rxnumevt) instead of hardcoding frames.min to
> 64.
>
> Signed-off-by: Jai Luthra <j-luthra@xxxxxx>
> ---
> sound/soc/ti/davinci-mcasp.c | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/sound/soc/ti/davinci-mcasp.c b/sound/soc/ti/davinci-mcasp.c
> index 1e760c315521..2a53fb7e72eb 100644
> --- a/sound/soc/ti/davinci-mcasp.c
> +++ b/sound/soc/ti/davinci-mcasp.c
> @@ -70,6 +70,7 @@ struct davinci_mcasp_context {
> struct davinci_mcasp_ruledata {
> struct davinci_mcasp *mcasp;
> int serializers;
> + u8 numevt;
> };
>
> struct davinci_mcasp {
> @@ -1470,12 +1471,13 @@ static int davinci_mcasp_hw_rule_format(struct snd_pcm_hw_params *params,
> static int davinci_mcasp_hw_rule_min_periodsize(
> struct snd_pcm_hw_params *params, struct snd_pcm_hw_rule *rule)
> {
> + struct davinci_mcasp_ruledata *rd = rule->private;
> struct snd_interval *period_size = hw_param_interval(params,
> SNDRV_PCM_HW_PARAM_PERIOD_SIZE);
> struct snd_interval frames;
>
> snd_interval_any(&frames);
> - frames.min = 64;
> + frames.min = rd->numevt;
64 was a nice number ;)
> frames.integer = 1;
>
> return snd_interval_refine(period_size, &frames);
> @@ -1516,6 +1518,9 @@ static int davinci_mcasp_startup(struct snd_pcm_substream *substream,
> if (mcasp->serial_dir[i] == dir)
> max_channels++;
> }
> + ruledata->numevt = (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) ?
> + mcasp->txnumevt :
> + mcasp->rxnumevt;
Do this at the same location where the rest of the ruledata members are
initialized, or
> ruledata->serializers = max_channels;
> ruledata->mcasp = mcasp;
> max_channels *= tdm_slots;
> @@ -1591,7 +1596,7 @@ static int davinci_mcasp_startup(struct snd_pcm_substream *substream,
>
> snd_pcm_hw_rule_add(substream->runtime, 0,
> SNDRV_PCM_HW_PARAM_PERIOD_SIZE,
> - davinci_mcasp_hw_rule_min_periodsize, NULL,
> + davinci_mcasp_hw_rule_min_periodsize, ruledata,
You could just pass a pointer to txnumevt/rxnumevt directly...
> SNDRV_PCM_HW_PARAM_PERIOD_SIZE, -1);
>
> return 0;
>
--
Péter
