[alsa-devel] snd-hda-intel - wallclk patch

[Takashi Iwai]

At Tue, 11 May 2010 10:44:17 +0200 (CEST),
Jaroslav Kysela wrote:
> 
> On Tue, 11 May 2010, Takashi Iwai wrote:
> 
> > At Tue, 11 May 2010 10:28:50 +0200 (CEST),
> > Jaroslav Kysela wrote:
> >>
> >> On Mon, 10 May 2010, Jaroslav Kysela wrote:
> >>
> >>> Hi,
> >>>
> >>> 	I would like to ask HDA gurus to check this patch (I will include it
> >>> to my tree once acked). The patch uses WALLCLK from HDA chips (marked as
> >>> required in the HDA specification) to check for bogus - too early - interrups
> >>> which confuses the upper PCM layer (sound skipping issues).
> >>>
> >>> 	More details about patch testing on problematic hardware can be found
> >>> at:
> >>>
> >>> 	https://bugzilla.kernel.org/show_bug.cgi?id=15912
> >>
> >> No objections received, so I pushed this code to my master/devel branches.
> >
> > Heh, that was quick, I had no time to review :)
> >
> > The change looks good to me.  Thanks for your fix (and rebasing).
> >
> > One thing is that you removed bdl_pos_adj=0 check.  This was there
> > explicitly to avoid the delayed irq handling no matter whether the
> > value is correct or not.  I guess it's safer to take it back, or
> > give any other way for user to avoid the delayed irq handling.
> 
> I see. But I need the pos % period_bytes check too. What about this 
> change?

With bdl_pos_adj==0, it should return 1 (non-error), but otherwise
this should be OK, I guess.


thanks,

Takashi


> diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
> index 0a6c55b..6674841 100644
> --- a/sound/pci/hda/hda_intel.c
> +++ b/sound/pci/hda/hda_intel.c
> @@ -1910,9 +1910,11 @@ static int azx_position_ok(struct azx *chip, struct azx_dev *azx_dev)
> 
>   	if (WARN_ONCE(!azx_dev->period_bytes,
>   		      "hda-intel: zero azx_dev->period_bytes"))
> -		return 0; /* this shouldn't happen! */
> +		/* this shouldn't happen! */
> +		return bdl_pos_adj[chip->dev_index] ? 0 : -1;
>   	if (pos % azx_dev->period_bytes > azx_dev->period_bytes / 2)
> -		return 0; /* NG - it's below the period boundary */
> +		/* NG - it's below the period boundary */
> +		return bdl_pos_adj[chip->dev_index] ? 0 : -1;
>   	azx_dev->start_wallclk = wallclk;
>   	return 1; /* OK, it's fine */
>   }
> 
> -----
> Jaroslav Kysela <perex at perex.cz>
> Linux Kernel Sound Maintainer
> ALSA Project, Red Hat, Inc.
>