Re: sound/core/pcm_lib.c:158: BUG

[Takashi Iwai <tiwai@suse.de>]

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At Sat, 18 Dec 2004 19:34:12 -0500,
Lee Revell wrote:
> 
> On Sun, 2004-12-19 at 00:53 +0100, Olaf Hering wrote:
> > Is this just debug output, or should I be worried about it?
> > 
> > linux-2.6.10-rc3-olh/sound/core/pcm_lib.c:158: BUG: stream = 0, pos = 0x4000, buffer size = 0x4000, period size = 0x1000
> > 
> > This is an ibook2, playing mp3 with xmms, alsa version is 1.0.3, from sles9.
> > I remember no failures in the last couple hours.
> 
> That message indicates that the hardware pointer returned by the pointer
> callback was beyond the end of the buffer which should not be possible.
> 
> This could indicate an off by one error in the driver, it looks like the
> erroneous position is one sample past the end of the buffer.

Does the patch below work?


Takashi

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Index: alsa-kernel/ppc/pmac.c
===================================================================
RCS file: /suse/tiwai/cvs/alsa/alsa-kernel/ppc/pmac.c,v
retrieving revision 1.51
diff -u -r1.51 pmac.c
--- alsa-kernel/ppc/pmac.c	15 Dec 2004 21:45:54 -0000	1.51
+++ alsa-kernel/ppc/pmac.c	20 Dec 2004 14:06:46 -0000
@@ -318,7 +318,8 @@
 	stat = ld_le16(&cp->xfer_status);
 	if (stat & (ACTIVE|DEAD)) {
 		count = in_le16(&cp->res_count);
-		count = rec->period_size - count;
+		if (count)
+			count = rec->period_size - count;
 	}
 #endif
 	count += rec->cur_period * rec->period_size;