linux-kernel - Re: sound skipping regression introduced in 2.6.30-rc8

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Date:	Thu, 11 Jun 2009 16:23:04 +0200
From:	Takashi Iwai <tiwai@...e.de>
To:	Bartlomiej Zolnierkiewicz <bzolnier@...il.com>
Cc:	David Miller <davem@...emloft.net>, linux-kernel@...r.kernel.org
Subject: Re: sound skipping regression introduced in 2.6.30-rc8

At Thu, 11 Jun 2009 16:14:07 +0200,
Bartlomiej Zolnierkiewicz wrote:
> 
> On Thursday 11 June 2009 15:56:14 Takashi Iwai wrote:
> > At Thu, 11 Jun 2009 15:32:33 +0200,
> > Bartlomiej Zolnierkiewicz wrote:
> > > 
> > > On Thursday 11 June 2009 14:02:20 David Miller wrote:
> > > > From: Takashi Iwai <tiwai@...e.de>
> > > > Date: Wed, 10 Jun 2009 21:37:14 +0200
> > > > 
> > > > > Also, it'd be helpful if you can check whether the problem exists in
> > > > > the current sound git tree (for-linus branch), too.
> > > > >   git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6.git for-linus
> > > > 
> > > > Same behavior as 2.6.30, but debugging messages are formatted differently
> > > > :-)
> > > > 
> > > > [ 1109.062182] PCM: Lost interrupts? (stream=0, delta=16384, intr_ptr=73728)
> > > > [ 1125.126123] PCM: Lost interrupts? (stream=0, delta=16384, intr_ptr=861184)
> > > > [ 1131.398094] PCM: Lost interrupts? (stream=0, delta=16384, intr_ptr=1178624)
> > > > [ 1135.579406] PCM: Lost interrupts? (stream=0, delta=16384, intr_ptr=1395712)
> > > > [ 1145.115367] PCM: Lost interrupts? (stream=0, delta=16384, intr_ptr=1869824)
> > > > [ 1152.688670] PCM: Lost interrupts? (stream=0, delta=16384, intr_ptr=2249728)
> > > 
> > > [ Just another data point. ]
> > > 
> > > I'm experiencing similar problem with the sound in recent -next kernels.
> > 
> > Which driver?
> 
> snd_intel8x0
> 
> > > Though the only debug data that I'm getting with xrun_debug == 1 is:
> > > 
> > > XRUN: pcmC0D0p:0
> > > XRUN: pcmC0D0p:0
> > > XRUN: pcmC0D0p:0
> > > XRUN: pcmC0D0p:0
> > > XRUN: pcmC0D0p:0
> > > 
> > > with xrun_debug == 3:
> > > XRUN: pcmC0D0p:0
> > > Pid: 4718, comm: audacious Not tainted 2.6.30-next-20090611-07944-gc1b019d-dirty #21
> > > Call Trace:
> > 
> > The semantics of xrun_debug proc file was a bit changed.  Now it's
> > bit flags, and 4 corresponds to the additional jiffies check (1 is to 
> > show the debug message, 2 to show stack trace).
> > 
> > Try to set 5 to xrun_debug.  Do you get other messages?
> 
> With xrun_debug == 5 I get:
> 
> PCM: hw_ptr skipping! (pos=14336, delta=15893, period=1024, jdelta=3/90)
> PCM: hw_ptr skipping! (pos=11264, delta=15893, period=1024, jdelta=3/90)
> PCM: hw_ptr skipping! (pos=7168, delta=15888, period=1024, jdelta=3/90)
> PCM: hw_ptr skipping! (pos=8192, delta=15915, period=1024, jdelta=3/90)
> PCM: hw_ptr skipping! (pos=15360, delta=15888, period=1024, jdelta=3/90)
> XRUN: pcmC0D0p:0
> PCM: hw_ptr skipping! (pos=6144, delta=15890, period=1024, jdelta=3/90)
> PCM: hw_ptr skipping! (pos=3072, delta=15890, period=1024, jdelta=3/90)
> 
> [ They seem to be the same as reported by davem against 2.6.30. ]

Yes.

> and the skipping is gone.

Does the patch below fix the problem?
If not, how about to revert the commit below?

    commit da2436a23c038055b1da6fe30b6ea2886b1e07b0
    Author: Jaroslav Kysela <perex@...ex.cz>
    Date:   Mon Apr 13 21:31:25 2009 +0200
    [ALSA] intel8x0: do not use zero value from PICB register


thanks,

Takashi

---
diff --git a/sound/pci/intel8x0.c b/sound/pci/intel8x0.c
index 173bebf..e894da0 100644
--- a/sound/pci/intel8x0.c
+++ b/sound/pci/intel8x0.c
@@ -1077,8 +1077,8 @@ static snd_pcm_uframes_t snd_intel8x0_pcm_pointer(struct snd_pcm_substream *subs
 		ptr1 <<= ichdev->pos_shift;
 		ptr = ichdev->fragsize1 - ptr1;
 		ptr += position;
-		ichdev->last_pos = ptr;
-		ichdev->last_pos_jiffies = jiffies;
+		if (ptr >= ichdev->size)
+			ptr = 0;
 	} else {
 		ptr1 = jiffies - ichdev->last_pos_jiffies;
 		if (ptr1)
@@ -1086,9 +1086,9 @@ static snd_pcm_uframes_t snd_intel8x0_pcm_pointer(struct snd_pcm_substream *subs
 		ptr = ichdev->last_pos + ptr1 * ichdev->jiffy_to_bytes;
 		ptr %= ichdev->size;
 	}
+	ichdev->last_pos = ptr;
+	ichdev->last_pos_jiffies = jiffies;
 	spin_unlock(&chip->reg_lock);
-	if (ptr >= ichdev->size)
-		return 0;
 	return bytes_to_frames(substream->runtime, ptr);
 }
 
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