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

[Takashi Iwai <tiwai@suse.de>]

Hi,

At Fri, 24 Jan 2003 13:41:29 +0100,
Pieter Palmers wrote:
> 
> I took a look at the Intel AC97 2.2 specs. It seems that the behaviour
> described here is a AC97 2.2 recommendation. take a look at 1 & 2 of 5.2.1.

thanks!

> 5.2.1 AUX_OUT Options
> As identified in the previous section, there are three common uses for
> AC `97's second output.  AC `97 2.2  addresses all three uses by
> renaming the second output as AUX_OUT, Register 04h as Aux Out Volume,
> and the pins as AUX_OUT_L, AUX_OUT_C, and AUX_OUT_R.
> 
> Driver developers should be aware that the AC `97 AUX_OUT may be
> implemented in one of three ways:
> 
>      1.True line level out.Support for a true consumer
> equipment-compatible (10 k\Omega ) line level output that does not
> change with master volume settings. Either fixed or fixable via the
> independent volume controls in Register 04h, the output level provides a
> 1V RMS (2.8 V peak-to-peak) output level for a 0 dB gain PCM output
> stream. When implemented this way, AUX_OUT is equivalent to AC `97 2.1's
> LNLVL_OUT definitions.
> 
>      2.Headphone out.  AUX_OUT can be implemented to support integrated
> headphone amplifier with 32 \Omega  drive capability and independent
> volume control via Register 04h.  When implemented this way, AUX_OUT is
> equivalent to AC `97 1.03 original HP_OUT definitions
> 
>      3. 4-Channel out.  In Codecs that support 4-channel operation,
> AUX_OUT can be implemented to support the  additional (i.e. L&R
> Surround) outputs. When implemented this way, AUX_OUT will be referred
> to 4CH_OUT.  In 4CH_OUT implementations, L and R Surround output is
> controlled via Surround Volume  Register 38h, not Aux Out Volume 04h,
> and powered down via the PRJ (SDAC) bit in Register 2Ah.
> 
> AUX_OUT defaults to be LNLVL_OUT unless HP_OUT or 4CH_OUT support is
> detected.

hmm, then we need to implement the controls for the register 0x04 even
if RESET/ID4 is 0..?   currently, we build them only when RESET/ID4 is
detected.  but i've not known which chip has LNLVL without RESET/ID4.
needs to check the spec for each chip.

confusingly, there are ac97 chips which sets RESET/ID4 but uses
AUX_OUT as LNLVL, such as ALC200, ALC201A or ALC202A.
and on these chips, we have the problem as $SUBJECT states.

furthremore, ALC201/2 uses it as HP_OUT, even though they have the
same id as ALC201/2A! in this case, we need to check PCI subdev ID...


Takashi


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