On Fri, Nov 18, 2016 at 10:58:46AM +0530, Vinod Koul wrote:
On Thu, Nov 17, 2016 at 02:35:15PM +0800, Grace Kao wrote:
256FS sysclk gives the best audio quality per nau8825 datasheet.
Loud headphone pop happens if there is no sysclk during nau8825 playback power up sequence. Currently Skylake does not output MCLK/FS when the back-end DAI op hw_param is called, so we cannot switch to MCLK/FS in hw_param. This patch reduces pop by leting nau8825 keep using its internal VCO clock during widget power up sequence, until SNDRV_PCM_TRIGGER_START when MCLK/FS is available.
<snip>
+static int skylake_nau8825_trigger(struct snd_pcm_substream *substream, int cmd) +{
- struct snd_soc_pcm_runtime *rtd = substream->private_data;
- struct snd_pcm_runtime *runtime = substream->runtime;
- struct snd_soc_dai *codec_dai = rtd->codec_dai;
- int ret = 0;
- switch (cmd) {
- case SNDRV_PCM_TRIGGER_START:
ret = snd_soc_dai_set_sysclk(codec_dai, NAU8825_CLK_FLL_FS, 0,SND_SOC_CLOCK_IN);if (ret < 0)dev_err(codec_dai->dev, "can't set FS clock %d\n", ret);ret = snd_soc_dai_set_pll(codec_dai, 0, 0, runtime->rate,runtime->rate * 256);if (ret < 0)dev_err(codec_dai->dev, "can't set FLL: %d\n", ret);break;starting clock on trigger doesnt sound right to me..
Me neither can't trigger be called from an atomic context? In which case I would expect operations on an external CODEC to be very likely to cause issues.
Thanks, Charles