[alsa-devel] [PATCH 14/31] HDA patch_via.c: Add Jack detect feature for VT1708.

[Takashi Iwai]

At Wed, 7 Oct 2009 13:56:35 +0800,
Li Bo wrote:
> 
> On Tue, Oct 6, 2009 at 11:34 PM, Takashi Iwai <tiwai at suse.de> wrote:
> > At Tue, 6 Oct 2009 23:27:35 +0800,
> > Li Bo wrote:
> >>
> >> On Tue, Oct 6, 2009 at 8:38 PM, Takashi Iwai <tiwai at suse.de> wrote:
> >> > At Tue, 6 Oct 2009 14:17:40 +0200,
> >> > Harald Welte wrote:
> >> >>
> >> >> Hi all,
> >> >>
> >> >> On Tue, Oct 06, 2009 at 08:01:40AM +0200, Takashi Iwai wrote:
> >> >>
> >> >> > > As you describe, we implement it with self-reschedule workqueue, acting
> >> >> > > like a timer.
> >> >> > > Is there some advice to implement timer-like task, I tested  with timer and
> >> >> > > it will crash the driver.
> >> >> >
> >> >> > Right, you can't call it in a softirq.
> >> >> >
> >> >> > A few problems, however:
> >> >> > - present variable should be in struct via_spec, instead of a static
> >> >> >   variable in update_hp_jack_state().
> >> >>
> >> >> I agree
> >> >> > - This mechanism is unconditionally invoked on VT1708 although, in
> >> >> >   theory, you can have a hardware that doesn't need HP jack detection
> >> >>
> >> >> Yes, Logan/Li/Lydia: If we generate this kind of workaround with a timer,
> >> >> it should only be used on those particular chips that absolutely need it.
> >> >
> >> > As far as I see, the code is only for VT1708, so it's already specific
> >> > to the codec chip.  But, even with this chip, you might have a pin
> >> > configuration that doesn't need the HP jack detection.
> >> >
> >>
> >> Yes, it's only for VT1708, and HP exists on most cases, and so HP jack detection
> >> are needed.
> >> And present will put into via_spec.
> >
> > If it's restricted only during the opened (better running) PCM stream,
> > it's not too bad.  But, it'd be even better to check the availability
> > of HP jack.
> >
> Sorry about analog loopback is not considered, I think analog loopback
> mute/unmute
> callback should also be added, is that OK?

Honestly, I think we can remove the analog-loopback part completely
for VT1708 + HP-jack.  If the loopback is inevitably needed, you can add
a check of codec "hint" interface to determine whether to build the
HP-jack detection or not at probing.
About hints, look at snd_hda_get_bool_hint() and HD-Audio.txt.


thanks,

Takashi