[alsa-devel] [PATCH] ALSA: hda - Remove ignore_misc_bit

Takashi Iwai tiwai at suse.de
Fri Sep 7 14:36:57 CEST 2012

At Fri, 07 Sep 2012 14:17:58 +0200,
David Henningsson wrote:
> On 09/07/2012 01:59 PM, Takashi Iwai wrote:
> > At Fri, 07 Sep 2012 13:26:35 +0200,
> > David Henningsson wrote:
> >>
> >> On 09/07/2012 12:01 PM, Takashi Iwai wrote:
> >>> At Fri,  7 Sep 2012 07:25:44 +0200,
> >>> David Henningsson wrote:
> >>>>
> >>>> The purpose of this flag is unclear. If the problem is that some machines
> >>>> have broken misc/NO_PRESENCE bits, they should be fixed by pin fixups.
> >>>>
> >>>> In addition, this causes jack detection functionality to be flawed on
> >>>> the M31EI, where there are two jacks without jack detection (which is
> >>>> properly marked as NO_PRESENCE), but due to ignore_misc_bit, these
> >>>> jacks are instead being reported as being present but always unplugged.
> >>>>
> >>>> BugLink: https://bugs.launchpad.net/bugs/939161
> >>>> Signed-off-by: David Henningsson <david.henningsson at canonical.com>
> >>>
> >>> So this will fix this one case but will break some others certainly.
> >>> It's a difficult to judge, but more removal is better, so I'll take
> >>> this.
> >>
> >> Ok. Do you have a sense for how many machines that will regress due to
> >> this patch? If it is common to set all pins to the wrong value, maybe
> >> its the M31EI that is the exception.
> >
> > Maybe a few Acer and ASUS ones with old codecs.
> > Possibly some desktops with unknown mobos might hit, but that's not
> > what I do care so much for now.
> Hrm, ok. I still don't like the idea of regressing machines...maybe this 
> patch needs further research.

Well, let's see.  I guess a problem will pop up anyway a few kernel
release later.  People with such machines rarely follow the kernel
development soonish.

> >>> But I still wonder why PulseAudio cares the headphone jack state even
> >>> though this has only one output at all?
> >>
> >> When seeing the system as a whole, there can be other outputs on other
> >> cards - HDMI, USB etc. If somebody e g plugs a USB headset in it will be
> >> simpler for the user if PulseAudio does not also show the unplugged 3.5
> >> mm jack.
> >
> > OK, but masking it out unconditionally isn't always nice.  There are
> > always corner cases...
> Not sure what corner case you mean here, but if you like, you can 
> configure this behaviour in 
> /usr/share/pulseaudio/alsa-mixer/paths/analog-output-headphones.conf, 
> causing the jack detection to be ignored if you prefer. And you can 
> quirk a specific machine to use another .conf file based on udev rules.
> Or is the corner case that ALSA don't give the correct jack detection 
> value? If so I prefer it to be fixed in ALSA ;-)

Well, I can think of different cases: BIOS is broken, my hardware is
broken and the driver is broken.  In such a case, an easier test would
be to disable this jack auto-things in PA, rather than fiddling with
the pin config and reconfigure the driver, so I hoped there might be
an intuitive and easy way to do that.


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