[alsa-devel] [RFC PATCH] HDA: Generic input jack handling

Takashi Iwai tiwai at suse.de
Fri Oct 7 17:27:05 CEST 2011

At Fri, 07 Oct 2011 17:11:38 +0200,
David Henningsson wrote:
> On 10/07/2011 03:03 PM, Takashi Iwai wrote:
> > At Fri, 07 Oct 2011 14:46:07 +0200,
> > David Henningsson wrote:
> >>
> >> On 10/07/2011 02:08 PM, Takashi Iwai wrote:
> >>> At Fri, 07 Oct 2011 13:49:46 +0200,
> >>> David Henningsson wrote:
> >>>>
> >>>> So, this is what I had in mind for 3.2. Assuming positive feedback from
> >>>> Takashi I'll go ahead and make a real patch out of this, and to clean up
> >>>> the Realtek implementation, as well as probably add this method for more
> >>>> codecs.
> >>>>
> >>>> Thoughts:
> >>>>
> >>>> 1) The unsol event tags vary wildly between different vendors. How about
> >>>> standardising that as well?
> >>>
> >>> Generalization is good.  But tags aren't always constant.  It'd be
> >>> better to assign each tag dynamically like in patch_sigmatel.c.
> >>> The reason is that you'd need to know the pin NID from the unsol
> >>> event, so the tag has to be unique even for the same purpose.  E.g. if
> >>> a machine has two headphones, both are the same type but they should
> >>> issue unsol events with different tags.
> >>
> >> One would think that this is an area where it shouldn't differ between
> >> vendors (after all, they need to do the same things, so this is just
> >> different implementations), but we can clean that up later, and when
> >> that is done we could consider standardising on having the nid as the
> >> unsol tag value.
> >> Anyway, as the patch below stands, sigmatel would call the function with
> >> unsol_tags->unsol_tag = 0, and then enable the jack itself.
> >>
> >> Did you think the patch looked good otherwise?
> >
> > Reporting per jack type isn't necessarily correct, e.g. when multiple
> > pins for the same type are present.  In that case, only the changed
> > pin should be reported.  So, in patch_realtek.c, the tag should be
> > also individual for each pin like in patch_sigmatel.c.
> > Currently it's using constants because of the model quirks.  Once when
> > these are removed, we can move to the dynamic allocation.
> Ok. I was afraid you would consider such a change too big to reach 3.2, 
> and current handling does not make things worse, really - it's just 
> slightly inoptimal to detect one more jack, but does not hurt much.
> Would you like me to add an associate tag -> nid array?

Well, the point is that this is a try to move a function into the core
code although you know it'll need a fix.  And this is no bug fix, but
a code clean-up.  It's very nice, but still it's to be done not to
break / worsen things.

That being said, I'm inclined to delay it for 3.3.  Now is so close to
the merge window and we don't need to rush for a refactoring patch.
It can be done more safely in the early development cycle.
Sorry if it disappoints you.

And, yes, it'd be nice if you can give a patch for tag->nid
association, too ;)



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