[alsa-devel] explicit commandline control of speakers vs headphone output

Eric Holstege eric_holstege at yahoo.com
Fri Aug 27 21:49:41 CEST 2010

Thanks for the info. (FYI, I have a Windtop 2200 All-in-one touchscreen, 
on which I'm building an appliance with, among other things, VOIP phone 
and answering machine capability).  I want the user to be able to "put 
the call on speaker" even if the mic/headphone handset is plugged in.

Can amixer override this automuting. Is it that the driver just sets the 
speakers to mute *at the time* the headphone is plugged in, or does it 
force them mute *so long as* the headphone is plugged in?

Or, regarding the pin_configs possibility, I guess I somehow edit
(or maybe user_pin_configs?).   Could one point me to documentation on 
what the bits mean? Mine are:
0x11 0x411111f0
0x12 0x411111f0
0x14 0x01014010
0x15 0x411111f0
0x16 0x99130120
0x17 0x411111f0
0x18 0x01a19850
0x19 0x99a3095f
0x1a 0x411111f0
0x1b 0x99130130
0x1c 0x411111f0
0x1d 0x4004022b
0x1e 0x01451140
0x1f 0x411111f0


David Henningsson wrote:
> 2010-08-27 20:46, Eric Holstege skrev:
>> Thanks, Clemens;
>> How were you able to determine that from the "amixer scontents" output.
>> Although I can't disable *automatic* speaker mute on headphone 
>> insertion, can I explicitly unmute them again (e.g. with amixer sset or 
>> cset)?
>> If not....
>> "cat /proc/asound/card*/codec*" says it is the Realtek ALC888.
>> Does this mean I have to somehow patch the kernel sound module file
>> .../linux-source-2.6.*/sound/pci/hda/patch_realtek.c
>> to fix this somehow?
> So in the long run, I think it would be better to leave all auto-muting
> to userspace. Then stuff like pulseaudio could to advanced decision of
> how to handle input events. But that's the long way.
> There are certainly ways to disable auto-muting for Realtek ALC888, look
> along the lines of "speaker_automute" and "unsol_event". It is also
> possible that you could tweak your user_pin_config to trick your HP out
> into a Line Out. That way it won't automute, and you don't have to
> recompile your kernel.
> As a side note: The VIA HDA driver, I believe, have an option for
> turning automute off. But it also sets "mute" on a misnamed control at
> the same time, tricking PA into believing that you want to mute all
> output. So PA is "helpful" and mutes everything else as well. :-/


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