Re: [RFC PATCH 05/16] ASoC: Intel: sof-pcm512x: reconfigure sclk in hw_params if needed

On Thu, Apr 09, 2020 at 02:58:30PM -0500, Pierre-Louis Bossart wrote:

The SCLK is resumed by the codec driver. In case the rate specified in hw_params does not match the current configuration, disable, set the new rate and restart the clock.

There is no operation on hw_free, the codec suspend routine will disable/deprepare the clock.

Note that we don't change the DAI configuration when the DAC+ PRO is detected. All changes for the codec master mode are handled in the topology file (DAI configuration change and scheduling change)

...

• err = snd_interval_ratnum(hw_param_interval(params,

• 				    SNDRV_PCM_HW_PARAM_RATE),
  

• 		  1, &rats_no_pll, &num, &den);
  

• if (err >= 0 && den) {

Perhaps usual pattern, i.e.

if (err < 0 || !den) return 0; (so, above seems optional configuration)

params...; return 0;

• params->rate_num = num;
  

• params->rate_den = den;
  

• }
• return 0;

...

+static int aif1_hw_params(struct snd_pcm_substream *substream,

• 	  struct snd_pcm_hw_params *params)
  

+{

• struct snd_soc_pcm_runtime *rtd = substream->private_data;
• struct sof_card_private *ctx = snd_soc_card_get_drvdata(rtd->card);
• struct device *dev = rtd->card->dev;
• int current_rate;
• int sclk_rate;
• int channels;
• int width;
• int rate;
• int ret = 0;

• if (ctx->is_dac_pro) {

if (!...) return 0;

...and drop the redundant ret assignment above.

• rate = params_rate(params);
  

• channels = params_channels(params);
  

• width = snd_pcm_format_physical_width(params_format(params));
  

• if (rate % 24000)
  

• 	sclk_rate = 22579200;
  

• else
  

• 	sclk_rate = 24576000;
  

• current_rate = clk_get_rate(ctx->sclk);
  

• if (current_rate != sclk_rate) {
  

• 	/*
  

• 	 * The sclk clock is started and stopped by the codec
  

• 	 * resume/suspend functions. If the rate isn't correct,
  

• 	 * stop, set the new rate and restart the clock
  

• 	 */
  

• 	dev_dbg(dev, "reconfiguring SCLK to rate %d\n",
  

• 		sclk_rate);
  

• 	clk_disable_unprepare(ctx->sclk);
  

• 	ret = clk_set_rate(ctx->sclk, sclk_rate);
  

• 	if (ret) {
  

• 		dev_err(dev, "Could not set SCLK rate %d\n",
  

• 			sclk_rate);
  

• 		return ret;
  

• 	}
  

• 	ret = clk_prepare_enable(ctx->sclk);
  

• 	if (ret) {
  

• 		dev_err(dev, "Failed to enable SCLK: %d\n",
  

• 			ret);
  

• 		return ret;
  

• 	}
  

• }
  

• ret = aif1_update_rate_den(substream, params);
  

• if (ret) {
  

• 	dev_err(dev, "Failed to update rate denominator: %d\n", ret);
  

• 	return ret;
  

• }
  

Do you still need below steps when current_rate == sclk_rate?

• ret = snd_soc_dai_set_bclk_ratio(rtd->codec_dai,
  

• 				 channels * width);
  

• if (ret) {
  

• 	dev_err(dev, "Failed to set bclk ratio : %d\n", ret);
  

• 	return ret;
  

• }
  

• }
• return ret;

+}