[alsa-devel] CX20724 headset button detect

[Takashi Iwai]

On Wed, 04 Apr 2018 13:30:12 +0200,
David Woodhouse wrote:
> 
> I have an HP EliteBook 850 G3 with CX20724:
> 
>  hdaudioC0D0: CX20724: BIOS auto-probing.
>  hdaudioC0D0: action: 0 gpio_led: 0
>  hdaudioC0D0: autoconfig for CX20724: line_outs=1 (0x16/0x0/0x0/0x0/0x0) type:line
>  hdaudioC0D0:    speaker_outs=1 (0x17/0x0/0x0/0x0/0x0)
>  hdaudioC0D0:    hp_outs=1 (0x1d/0x0/0x0/0x0/0x0)
>  hdaudioC0D0:    mono: mono_out=0x0
>  hdaudioC0D0:    inputs:
>  hdaudioC0D0:      Mic=0x19
>  hdaudioC0D0:      Internal Mic=0x1a
>  hdaudioC0D0:      Line=0x18
>  hdaudioC0D0: Enable sync_write for stable communication
>  hdaudioC0D0: action: 1 gpio_led: 0
>  hdaudioC0D0: action: 2 gpio_led: 0
>  ...
>  input: HDA Intel PCH Mic as /devices/pci0000:00/0000:00:1f.3/sound/card0/input21
> 
> The CX20724 datasheet¹ suggests that it supports headset button events
> — at least 'Function A' when the mic pin is shorted to ground, if not
> the other functions.
> 
> But it isn't working. Only the jack insertion is reported through the
> corresponding input device, not the button press. I added a printk into
> snd_hda_jack_unsol_event(), and it isn't even being invoked at all for
> the button presses; only insertion/removal.
> 
> How do we make this work?

Unfortunately, there is no standard definition for the headset button
handling in HD-audio spec, and each vendor implements in own way
without disclosure.
For example, the datasheet you gave also doesn't shed any light how
it's triggered (the headset button widget NID is empty and no more
information).

So at this moment, only Conexant people can answer to this question
properly, sorry.

Maybe you can try to enable the GPIO unsolicited event and see whether
any unsolicited event is generated.  Though, the datasheet says it's
something else individual, but who knows.


thanks,

Takashi

> 
> 
> ¹ https://www.tonymacx86.com/attachments/datasheet_cx20724-pdf.203615/
> [1.2 smime.p7s <application/x-pkcs7-signature (base64)>]
> 
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