Re: intel8x0 dual codec issue

[Takashi Iwai <tiwai@suse.de>]

[-- Attachment #1: Type: text/plain, Size: 1430 bytes --]

At Mon, 07 Feb 2005 23:43:39 -0500,
Ron Cococcia wrote:
> 
> Hello,
> 
> I'm having a little trouble with a dual codec setup that I am using. 
> The motherboard has an Intel 815 chip (82801BAICH2).  The motherboard 
> has the primary (00) codec, which is an AD1885.  A secondary (01) codec 
> has been added over a CNR connector.  This one is a CS4299.  The 
> secondary codec uses the timing values generated by the primary.
> 
> I had been hearing some distortion in the audio.  It was quite 
> noticeable.  Using a wav file of sine waves that has different 
> frequencies (440, 880, 1760, 3520) at 44100Hz, I could see that there 
> was some jitter on a scope.  As the frequencies went up, it got worse. 
> I then created another test file with the same frequencies, but sampled 
> at 48000Hz.  Playback of that audio was extremely clean on the scope.
> 
> Looking into it more, I noticed that the PCM front DAC (ac97#1-1) was 
> not adjusting itself to the appropriate frequency.  The DAC on the 
> primary codec was switching between 44100Hz and 48000Hz when I played 
> the different samples.
> 
> I'd like to have the secondary codec reflect the output rate that is 
> being sent to it.  How might I get it to do this?  Is it a bug (should 
> the codec front DAC on the secondary codec reflect the appropriate 
> frequency?), or how is it intended to work?

I guess it's a bug.  Could you try the attached patch?


Takashi

[-- Attachment #2: Type: text/plain, Size: 701 bytes --]

Index: alsa-kernel/pci/ac97/ac97_pcm.c
===================================================================
RCS file: /suse/tiwai/cvs/alsa/alsa-kernel/pci/ac97/ac97_pcm.c,v
retrieving revision 1.19
diff -u -r1.19 ac97_pcm.c
--- alsa-kernel/pci/ac97/ac97_pcm.c	27 Dec 2004 13:19:32 -0000	1.19
+++ alsa-kernel/pci/ac97/ac97_pcm.c	10 Feb 2005 17:19:45 -0000
@@ -602,8 +602,10 @@
 					snd_printk(KERN_ERR "invalid AC97 slot %i?\n", i);
 					continue;
 				}
+#if 0
 				if (reg_ok & (1 << (reg - AC97_PCM_FRONT_DAC_RATE)))
 					continue;
+#endif
 				//printk(KERN_DEBUG "setting ac97 reg 0x%x to rate %d\n", reg, rate);
 				err = snd_ac97_set_rate(pcm->r[r].codec[cidx], reg, rate);
 				if (err < 0)