Re: [alsa-devel] [PATCH 7/8] ASoC: wm8998: Initial WM8998 codec driver

On Tue, Apr 21, 2015 at 01:33:55PM +0100, Richard Fitzgerald wrote:

+static int wm8998_in1mux_ev(struct snd_soc_dapm_widget *w,

• 		struct snd_kcontrol *kcontrol,
  

• 		int event)
  

+{

• struct snd_soc_codec *codec = snd_soc_dapm_to_codec(w->dapm);
• struct arizona *arizona = dev_get_drvdata(codec->dev->parent);
• unsigned int left_mux, right_mux, in1mode, old;
• switch (event) {
• case SND_SOC_DAPM_PRE_PMU:

• /* Validate the mux configuration */
  

• left_mux = snd_soc_read(codec, ARIZONA_ADC_DIGITAL_VOLUME_1L) &
  

• 		  ARIZONA_IN1L_SRC_MASK;
  

• right_mux = snd_soc_read(codec, ARIZONA_ADC_DIGITAL_VOLUME_1R) &
  

• 		  ARIZONA_IN1R_SRC_MASK;
  

• /* Only IN1A can be digital, IN1B is always analogue */
  

• in1mode = (arizona->pdata.inmode[0] & 2)
  

• 		<< (ARIZONA_IN1_MODE_SHIFT - 1);
  

• if (in1mode != 0) {
  

• 	/* if IN1A is digital, the only valid mux configs
  

• 	 * are both channels A or both channels B.
  

• 	 */
  

• 	if (left_mux != right_mux) {
  

• 		dev_err(arizona->dev,
  

• 			"IN1=DMIC and IN1L Mux != IN1R Mux");
  

• 		return -EINVAL;
  

• 	}
  

This (or at least some of it) seems like something we should be doing by registering different widgets and routing at device probe time.

• old = snd_soc_read(codec, ARIZONA_IN1L_CONTROL) &
  

• 			ARIZONA_IN1_MODE_MASK;
  

• if (old != in1mode)
  

• 	snd_soc_update_bits(codec, ARIZONA_IN1L_CONTROL,
  

• 				ARIZONA_IN1_MODE_MASK, in1mode);
  

Why bother with the read into old here? Suppressing redundant updates is part of the point of snd_soc_update_bits().