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Deferring Audio Device Probe

Question asked by on Oct 18, 2019
Latest reply on Oct 20, 2019 by Victor Linnik



We are working on a custom board based on IMX-7d running Android. The board uses an audio codec (WM5110), audio DSP (with custom firmware) that is part of the codec's digital core and an audio switch connected to the headphone jack. As it stands, the DSP bootup is triggered by the ALSA PCM core and occurs much later after all the device probes (including both the codec and audio switch probes) and this is something of a black box to us. 


We'd however like to defer the audio switch probe to after the DSP boot is complete. How do we go about doing this? Specifically, how do we expose the DSP boot status (see: kernel_imx/sound/soc/codecs/wm_adsp.c) to the audio switch driver and what mechanisms are preferred for deferring probe in a way that doesn't adversely impact the boot-time?