linux-kernel - Re: [PATCH v2 2/2] ASoC: ti: davinci-mcasp: Set min period size using FIFO config

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Date: Mon, 10 Jun 2024 17:47:34 +0300
From: Péter Ujfalusi <peter.ujfalusi@...il.com>
To: Jai Luthra <j-luthra@...com>, Lars-Peter Clausen <lars@...afoo.de>,
 Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.com>,
 Liam Girdwood <lgirdwood@...il.com>, Mark Brown <broonie@...nel.org>
Cc: linux-sound@...r.kernel.org, linux-kernel@...r.kernel.org,
 alsa-devel@...a-project.org, Devarsh Thakkar <devarsht@...com>,
 Vignesh Raghavendra <vigneshr@...com>, Jayesh Choudhary <j-choudhary@...com>
Subject: Re: [PATCH v2 2/2] ASoC: ti: davinci-mcasp: Set min period size using
 FIFO config

Hi,

On 6/10/24 1:56 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.

Thank you the patch and the fix,
Acked-by: Peter Ujfalusi <peter.ujfalusi@...il.com>

> 
> Signed-off-by: Jai Luthra <j-luthra@...com>
> ---
>  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..2b1ed91a736c 100644
> --- a/sound/soc/ti/davinci-mcasp.c
> +++ b/sound/soc/ti/davinci-mcasp.c
> @@ -1472,10 +1472,11 @@ static int davinci_mcasp_hw_rule_min_periodsize(
>  {
>  	struct snd_interval *period_size = hw_param_interval(params,
>  						SNDRV_PCM_HW_PARAM_PERIOD_SIZE);
> +	u8 numevt = *((u8 *)rule->private);
>  	struct snd_interval frames;
>  
>  	snd_interval_any(&frames);
> -	frames.min = 64;
> +	frames.min = numevt;
>  	frames.integer = 1;
>  
>  	return snd_interval_refine(period_size, &frames);
> @@ -1490,6 +1491,7 @@ static int davinci_mcasp_startup(struct snd_pcm_substream *substream,
>  	u32 max_channels = 0;
>  	int i, dir, ret;
>  	int tdm_slots = mcasp->tdm_slots;
> +	u8 *numevt;
>  
>  	/* Do not allow more then one stream per direction */
>  	if (mcasp->substreams[substream->stream])
> @@ -1589,9 +1591,12 @@ static int davinci_mcasp_startup(struct snd_pcm_substream *substream,
>  			return ret;
>  	}
>  
> +	numevt = (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) ?
> +			 &mcasp->txnumevt :
> +			 &mcasp->rxnumevt;
>  	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, numevt,
>  			    SNDRV_PCM_HW_PARAM_PERIOD_SIZE, -1);
>  
>  	return 0;
> 

-- 
Péter