[alsa-devel] [PATCH] [RFC 8/13] Intel SST sound card driver

[Takashi Iwai]

At Tue, 7 Jul 2009 12:34:16 +0530,
Harsha, Priya wrote:
> 
> 
> 
> >-----Original Message-----
> >From: Takashi Iwai [mailto:tiwai at suse.de]
> >Sent: Tuesday, July 07, 2009 12:19 PM
> >To: Harsha, Priya
> >Cc: Koul, Vinod; alsa-devel at alsa-project.org
> >Subject: Re: [alsa-devel] [PATCH] [RFC 8/13] Intel SST sound card driver
> >
> >At Tue, 7 Jul 2009 11:50:46 +0530,
> >Harsha, Priya wrote:
> >>
> >> >
> >> >> +	.access 	=	SNDRV_CTL_ELEM_ACCESS_READWRITE,
> >> >> +	.info 		=	snd_intelmad_line_volume_info,
> >> >> +	.get 		=	snd_intelmad_volume_get,
> >> >> +	.put		=	snd_intelmad_volume_set,
> >> >
> >> >Can it have the dB information via TLV?
> >> No. It actually differs across the 3 sound cards supported and it's
> >> not a direct TLV that can be used.
> >
> >Then you'd set a static TLV entry after creating the ctl element
> >instance, or return a TLV entry dynamically via the tlv callback.
> Sorry I misunderstood. The value that is passed in min and max is in
> dB. 
> For min and max values, it's a static dB value that I return. But
> when the volume adjustments need to be done, based on the value
> given by ALSA, I set the sound card registers to reflect that dB
> value.

The value to be set is always raw.  That is, alsa-lib computes the
raw value from the given dB value based on the TLV information (dB
min/max), supposing the volume scale is logarithmic.

Isn't it the case for you?

> When volume is queried for, I read the specific sound card
> register and return the dB value to ALSA. 
> Will this implementation be ok?


Takashi