Machine routing consideration

The machine driver can alter (or should I say append) the routes defined from within the codec. It has the last word on which codec pins must be used, for example.

Codec pins

Codec pins are meant to be connected to the board connectors. The available codec pins are defined in the codec driver using the SND_SOC_DAPM_INPUT and SND_SOC_DAPM_OUTPUT macros. These macros can be searched with the grep command in the codec driver in order to find the available PIN.

For example, the sgtl5000 codec driver defines the following output and input:

static const struct snd_soc_dapm_widget sgtl5000_dapm_widgets[] = {
    SND_SOC_DAPM_INPUT("LINE_IN"),
    SND_SOC_DAPM_INPUT("MIC_IN"),
    SND_SOC_DAPM_OUTPUT("HP_OUT"),
    SND_SOC_DAPM_OUTPUT("LINE_OUT"),
    SND_SOC_DAPM_SUPPLY("Mic Bias", SGTL5000_CHIP_MIC_CTRL...