[alsa-devel] Cherry Trail + RT5645 devices analog microphone not working.

[Bard Liao]

> -----Original Message-----
> From: Hans de Goede [mailto:hdegoede at redhat.com]
> Sent: Sunday, December 24, 2017 6:43 PM
> To: Bard Liao
> Cc: Pierre-Louis Bossart; alsa-devel at alsa-project.org
> Subject: Cherry Trail + RT5645 devices analog microphone not working.
> 
> Hi Bard,
> 
> I've been looking into getting the microphone to work on
> some Cherry Trail + RT5645 devices with what appears to
> be a simple analog microphone.
> 
> You can see the microphone on one of the models I'm trying
> to get it to work on soldered onto the right side of the PCB
> here: https://i.imgur.com/bJzBQWe.jpg
> 
> I'm using this ucm config:
> 
> https://fedorapeople.org/~jwrdegoede/chtrt5645/
> 
> Which is basically Pierre-Louis Bossart's config from:
> https://github.com/plbossart/UCM
> 
> Adjusted because the devices all have a mono speaker.
> 
> I've been trying to get this to work myself and I can get
> some sound while recording by adding:
> 
>                  cset "name='RECMIXL BST2 Switch' on"
>                  cset "name='RECMIXR BST2 Switch' on"
> 
> But then I mainly get noise, I do get some sound from the
> microphone if I talk really really loudly, but it is
> barely above the noise-floor. I've the feeling that BST2
> is only picking up the microphone via cross-talk and
> that BST1 indeed is the correct input, but for some reason
> I get complete silence when recording when only BST1 is
> selected in the RECMIXR, and yes I've checked / set the
> "IN1 boost volume".
> 
> TL;DR: I'm trying to get an analog mic to work on 3
> different models Cherry Trail + RT5645 devices and I've
> been unable to get this to work. I've put a registerdump
> of the rt5645 with gnome-sound-recorder running here:
> https://fedorapeople.org/~jwrdegoede/rt5645-mic-red.dump
> 
> Any insights / help with this would be very much
> welcome.

I don't have the schematic, but I think you probably need micbias
for the capture. Please add both "micbias1" and "micbias2" in
the audio route since I don't know which one is needed.
for example
static const struct snd_soc_dapm_route cht_rt5645_audio_map[] = {
...
	{"Int Mic", NULL, "micbias1"},
	{"Int Mic", NULL, "micbias2"},
...
};


> 
> Regards,
> 
> Hans
> 
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