[alsa-devel] [PATCH] ALSA: hda - Fix Dock Headphone on Thinkpad X250 seen as a Line Out

[Takashi Iwai]

At Wed, 24 Jun 2015 14:33:52 +0200,
David Henningsson wrote:
> 
> 
> 
> On 2015-06-24 14:10, Takashi Iwai wrote:
> > At Wed, 24 Jun 2015 13:06:05 +0200,
> > David Henningsson wrote:
> >>
> >>
> >>
> >> On 2015-06-24 11:00, Takashi Iwai wrote:
> >>> At Wed, 24 Jun 2015 10:46:33 +0200,
> >>> David Henningsson wrote:
> >>>>
> >>>> Thinkpad X250, when attached to a dock, has two headphone outs but
> >>>> no line out. Make sure we don't try to turn this into one headphone
> >>>> and one line out (since that disables the headphone amp on the dock).
> >>>>
> >>>> Alsa-info at http://www.alsa-project.org/db/?f=36f8764e1d782397928feec715d0ef90dfddd4c1
> >>>>
> >>>> Cc: stable at vger.kernel.org
> >>>> Signed-off-by: David Henningsson <david.henningsson at canonical.com>
> >>>
> >>> This is one of fixes I had in mind (and asked for testing in bugzilla
> >>> kernel.org report).
> >>
> >> Sorry, I'm missing context. What report?
> >>
> >>> One drawback by this is that the auto-mute
> >>> *between* the headphones won't work like before.  If one has expected
> >>> it, then this can be seen as a regression.
> >>
> >> Fair enough, we can drop stable from the patch since this could be seen
> >> as behavioural change rather than bug fix.
> >>
> >>> Another fix was to change this as a proper line-out.  This will keep
> >>> the current auto-mute behavior.
> >>>
> >>> OTOH, dealing both jacks equally is also not bad, per se.
> >>
> >> The tricky thing about routing is that everyone wants it different, so
> >> pleasing everyone seems to be an impossible equation :-/
> >>
> >> I would choose the default behaviour (headphone or line out) based on
> >> the icon on the jack. I should double-check that with someone who has
> >> the hardware. And then, if someone wants another behaviour then
> >> hdajackretask can be used. Or we can add a jack mode kcontrol for that
> >> jack, if you prefer, although I'd have to check how PulseAudio handles
> >> that (not that well, is my gut feeling).
> >
> > I have no preference in this regard.  My only slight concern was the
> > behavior change by this patch.  It has both sides, one can see as an
> > improvement while another as a regression.
> >
> > Currently I'm inclined to take this patch as is, since this would make
> > things working in a little obstacle.  Once when we get a real
> > regression report due to the lack of exclusive mute control, we may
> > provide another model option as a compromise.
> >
> > But, I'm open about this, really.  So, if anyone has a good argument,
> > let me know.
> 
> Anyhow, it looks like the current behaviour is not good, because we have 
> a "Dock Headphone Jack" on the same node as "Dock Line Out Playback 
> Switch". This makes me wonder if the HP -> LO fixup should be removed 
> altogether. Are there any machines these days that needs this fixup? In 
> case there were just a few of them in the past, maybe they should have 
> pin fixups instead?

Yes, this is one good step forward.  We should check through hda-emu.

Though, for the problem of Thinkpads, I prefer a patch with a smaller
impact like yours.


Takashi