Re: [Survey] headphone <-> master volume swap -- which codec chip?

[Takashi Iwai <tiwai@suse.de>]

At Fri, 24 Jan 2003 12:16:00 +0100 (CET),
Jaroslav wrote:
> 
> On Fri, 24 Jan 2003, Takashi Iwai wrote:
> 
> > Hi all,
> > 
> > there have been bug-reports regarding to the swapping of headphone
> > and master volumes.
> > i'd like to ask you to check which AC97 codec chip is used on which
> > board (or laptop) if you have such a problem.  if this happens only on
> > a certain chip model, we can add a quirk for that.
> 
> Takashi, this quirk can be done only by detection of subvendor and 
> subsystem from the PCI ID space.

yeah, the lspci output is on the query list.

> It's absolutely irrelevant which AC97 
> chip is used.

really?  i believe this happens only on certain ac97 chips.
for example, ALC202 spec says that ALC202A uses the headphone volume
as the "true line out" volume.  so, apparently, some ac97 chips
"recommend" this behavior.  let's see...

> Vendor might wire codec in any way. Also, some codecs may 
> swap line-out / headphone out via registers.

this is a different case, imo.
the problem is that we have no chance to detect/switch them, either
manually or automatically.

a general solution would be to add an ac97 control switch to swap
them.  then the accssed registers are exchanged internally according 
to this control.

but it isn't bad to know which chips and which machines have this
problem, so that we can add quirks to turn on this switch
automatically.


Takashi


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