Re: [PATCH v2] ASoC: fsl-asoc-card: Remove fsl_asoc_card_set_bias_level function

On Sun, Aug 02, 2020 at 10:22:35AM +0800, Shengjiu Wang wrote:

...

...

• /* Specific configuration for PLL */
  

• if (codec_priv->pll_id && codec_priv->fll_id) {
  

•         if (priv->sample_format == SNDRV_PCM_FORMAT_S24_LE)
  

•                 pll_out = priv->sample_rate * 384;
  

•         else
  

•                 pll_out = priv->sample_rate * 256;
  

•         ret = snd_soc_dai_set_pll(asoc_rtd_to_codec(rtd, 0),
  

•                                   codec_priv->pll_id,
  

•                                   codec_priv->mclk_id,
  

•                                   codec_priv->mclk_freq, pll_out);
  

•         if (ret) {
  

•                 dev_err(dev, "failed to start FLL: %d\n", ret);
  

•                 goto out;
  

•         }
  

•         ret = snd_soc_dai_set_sysclk(asoc_rtd_to_codec(rtd, 0),
  

•                                      codec_priv->fll_id,
  

•                                      pll_out, SND_SOC_CLOCK_IN);
  

Just came into my mind: do we need some protection here to prevent PLL/SYSCLK reconfiguration if TX/RX end up with different values?

Sorry, not really catching your point. could you please elaborate? Why do TX/RX end up with different values?

If TX and RX run concurrently but in different sample rates or sample formats, pll_out would be overwritten to PLL/SYSCLK?

I remember imx-wm8962 uses SSI, having symmetric flags for rates/ channels/samplebits, but fsl-asoc-card might have (or will have) other use case.

If all existing combinations don't have any problem, we can add a protection later when we need.