[PATCH v3 3/4] ALSA: hda/cirrus: Add jack detect interrupt support from CS42L42 companion codec.

[Pierre-Louis Bossart]

> @@ -38,6 +39,15 @@ struct cs_spec {
>   	/* for MBP SPDIF control */
>   	int (*spdif_sw_put)(struct snd_kcontrol *kcontrol,
>   			    struct snd_ctl_elem_value *ucontrol);
> +
> +	unsigned int cs42l42_hp_jack_in:1;
> +	unsigned int cs42l42_mic_jack_in:1;
> +
> +	struct mutex cs8409_i2c_mux;

what does this protect? there isn't any comment or explanations in the 
commit message.