NV10 hdac issue

Alexander Motin mav at FreeBSD.org
Wed May 23 18:32:57 UTC 2012

On 05/23/12 01:06, Konstantin Belousov wrote:
> I have (another) Atom motherboard from Intel, DN2800MT. Now, the problem
> is with distorted sound. Anything is played as if some pause is inserted
> after the next sample is finished. So I hear the proper pitch, but with
> guggle between fragments. I am not sure how to describe it better, except
> to say that it sounds as if buffering was not enough, for regular short
> intervals of approx. 0.5 sec.
> I do not believe that 1.8Hhz Atoms are too slow to decode mp3 or to play wav.
> The hda controller is
> hdac0 at pci0:0:27:0:      class=0x040300 card=0x20128086 chip=0x27d88086 rev=0x02 hdr=0x00
> codec is Realtek ALC888. The verbose dmesg from hda_snd load is at
> http://people.freebsd.org/~kib/tom.dmesg.txt , assuming this is useful.
> I would want to get normal sound from this board, thanks in advance.

I haven't seen alike reports neither for this controller, nor for this 
CODEC. I would try to experiment with:
1) disabling MSI interrupts with hint.hdac.0.msi=0
2) switching to polling mode without using any interrupts with 
3) changing buffer size with hw.snd.latency
4) changing playback format (or vchans format it it is used)
5) setting sysctl hw.snd.verbose=2 and checking for application level 
underruns with `cat /dev/sndstat`.

Alexander Motin

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