[Openvortex-dev] Low volume, distortion, etc

[Manuel Jander]

Hi,

I have been playing with some AC97 registers, and it semes,
that some of them made a difference. As i suspected, on the
Aureal chip side everything semes OK, but the codec config isn't
right.

Most Vortex 2 cards (MX300) have the STAC9708/11 codec, which has
a lot of extra "features". That includes a "Enable external AMplifier
PIO bit". After enabling it explicitly, the aoutput semes a lot louder.
Passing signal to a powererd down amplifier isnt a good idea anyway, and
it wouldnt surprise me is that causes distortion.
I'm not sure if these changes really are right. Its very late and im
sleepy, but if i'm not on crack, it really semes very louder now to me.
Thjis has to be changed inside of au88x0_mixer.c:

int __devinit snd_vortex_mixer(vortex_t *vortex) {
    ac97_t ac97;
        int result;
    memset(&ac97, 0, sizeof(ac97));
    // Intialize AC97 codec stuff.
    ac97.write = vortex_codec_write;
    ac97.read = vortex_codec_read;
    ac97.private_data = vortex;
        
        result = snd_ac97_mixer(vortex->card, &ac97, &vortex->codec);
        if (vortex->codec) {
                /* Disable -6dB input and output attenuation.  */
                vortex_codec_write(vortex->codec, 0x6c, 0x0);
                /* Enable external amplifier. This is for STAC9708/11           
codecs.
STAC9701/03 don't need this but doesnt harm. */
                vortex_codec_write(vortex->codec, 0x26, 0x8000);
        }
    return result;
}


Best Regards,

Manuel Jander.