[alsa-devel] [PATCH] ALSA: hda - using POS_FIX_LPIB on Broadwell HDMI Audio

[Yang, Libin]

Hi Takashi,

> -----Original Message-----
> From: Takashi Iwai [mailto:tiwai at suse.de]
> Sent: Thursday, May 8, 2014 1:51 PM
> To: Yang, Libin
> Cc: alsa-devel at alsa-project.org; Lin, Mengdong; Pierre-Louis Bossart
> Subject: Re: [PATCH] ALSA: hda - using POS_FIX_LPIB on Broadwell HDMI
> Audio
> 
> At Thu, 8 May 2014 05:48:04 +0000,
> Yang, Libin wrote:
> >
> > Hi Takashi,
> >
> > I checked the wallclock counter. The counter is OK. But it failed to correct
> the position.
> 
> So, how wrong the position buffer is?  Is the problem intermittent?
> Please elaborate more.

The issue is the position is almost always inaccurate. You will hear there is intermittent noise in the sound. And the sound is played faster than it should be.

The following message is what I got from dmesg:

[ 73.278117] snd_hda_intel 0000:00:03.0: IRQ timing workaround is activated for card #0. Suggest a bigger bdl_pos_adj.
[ 73.528575] snd_hda_intel 0000:00:03.0: Unstable LPIB (26240 >= 24064); disabling LPIB delay counting

Do you think the print of wallclk and position information in the function azx_position_ok() is useful to you? If yes, I will add debug code to print the info.

> 
> 
> Takashi
> 
> > This issue happens when we play sound on HDMI audio. We have tried
> with aplay and paplay.
> >
> > I have tried the buffer size of 16384, 8192 and 4096 and with the sample
> rate of 48KHz and 44.1KHz.
> >
> > Regards,
> > Libin
> >
> > > -----Original Message-----
> > > From: Takashi Iwai [mailto:tiwai at suse.de]
> > > Sent: Thursday, May 8, 2014 1:09 PM
> > > To: Yang, Libin
> > > Cc: alsa-devel at alsa-project.org; Lin, Mengdong; Pierre-Louis Bossart
> > > Subject: Re: [PATCH] ALSA: hda - using POS_FIX_LPIB on Broadwell
> > > HDMI Audio
> > >
> > > At Thu,  8 May 2014 02:03:24 +0800,
> > > libin.yang at intel.com wrote:
> > > >
> > > > From: Libin Yang <libin.yang at intel.com>
> > > >
> > > > Audio stream is not continuous if using position buffer on
> > > > Broadwell HDMI audio. Sound is clipped.
> > > > Fix this issue by using POS_FIX_LPIB.
> > >
> > > That's odd.  The recent Intel hardware has a wallclock support, so
> > > the position should be corrected by that.
> > >
> > > In which situation did the problem happen?  Did it happen with every
> > > application and any period/buffer setup?
> > >
> > >
> > > Takashi
> > >
> > > >
> > > > Signed-off-by: Libin Yang <libin.yang at intel.com>
> > > > ---
> > > >  sound/pci/hda/hda_intel.c | 1 +
> > > >  1 file changed, 1 insertion(+)
> > > >
> > > > diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
> > > > index b540ad7..9cd40c6 100644
> > > > --- a/sound/pci/hda/hda_intel.c
> > > > +++ b/sound/pci/hda/hda_intel.c
> > > > @@ -993,6 +993,7 @@ static struct snd_pci_quirk position_fix_list[] = {
> > > >  	SND_PCI_QUIRK(0x1565, 0x8218, "Biostar Microtech", POS_FIX_LPIB),
> > > >  	SND_PCI_QUIRK(0x1849, 0x0888, "775Dual-VSTA", POS_FIX_LPIB),
> > > >  	SND_PCI_QUIRK(0x8086, 0x2503, "DG965OT AAD63733-203",
> > > POS_FIX_LPIB),
> > > > +	SND_PCI_QUIRK(0x8086, 0x2010, "Broadwell HDMI audio",
> > > POS_FIX_LPIB),
> > > >  	{}
> > > >  };
> > > >
> > > > --
> > > > 1.8.3.2
> > > >
> >


Regards,
Libin