[alsa-devel] Regression for Lenovo X240 sound in 3.18

[Takashi Iwai]

At Tue, 30 Dec 2014 19:13:14 +0100 (CET),
Jan Engelhardt wrote:
> 
> 
> On Tuesday 2014-12-30 17:20, Takashi Iwai wrote:
> >
> >Ah, I see you disable the automute.  So the headphone plug shouldn't
> >matter.
> 
> Changing the "Auto-Mute" control does not do anything; the system always
> exhibits Automute behavior (if that's a bug, it's one which I did not
> care about so far).

Oh, that's really interesting.  I didn't expect such a
hardware-controlled automute nowadays.  We need to investigate this
more.

Could you try hda_analyzer or hda-jack-retask (see HD-Audio.txt) to
change the control of pins 0x14 and 0x15 on the fly?  Do they
influence on the output for the speaker (0x14) and the headphone
(0x15)?  Also, check alsa-info.sh output (or alsactl store) whether
"Headphone Jack" gives the right value per the headphone jack plug
state.

> >Hm, then there is nothing obvious wrong there at a quick glance.
> >Maybe there is an implicit fixed connection between a DAC and a pin?
> >Try the patch below.
> 
> With your patch, I get a system which still has two issues
> that were not there in 3.17:
>  - the "Headphone" control is present but has no volume bar
>  - the "PCM" control does not affect the Speaker volume

These are expected behavior (side-effects).  It's because of the
shared volume control between the headpohne and the dock output.
On 3.18, "PCM" is assigned to this shared volume control as a
fallback.  In your case, "PCM" was used by alsa-lib softvol plugin,
and this is no longer taken when a hardware volume control is
present.  That's the reason for the second item.

On 3.19, this was renamed differently, so that "PCM" can appear again
by a softvol item like before.

In anyway, beware that changing "PCM" softvol volume isn't wise at
all.  Better to keep this as unmodified (0dB, 100%) and use only
"Master" volume so that you can avoid unnecessary sample manipulations
in software.


Takashi