[alsa-devel] Strange Problem with snd-hda-intel

Frank Maik Kittelmann fkittelmann at formac.com
Tue May 8 10:41:04 CEST 2012

We have some strange behavior in our audio application using the ALC 888 
hardware in ubuntu 10.10 with the hda-intel driver . Basically the main 
problem seems to be a buffer or memory management issue. Once a playback 
is stopped the very last sample is repeated forever, independently from 
sampling rate or sound file format. This sample leads to a constant DC 
voltage after the DA converters.

We already tried the following steps:

1.) we changed a line in hda_intel.c to reset the fifo

--- a/sound/pci/hda/hda_intel.c
+++ b/sound/pci/hda/hda_intel.c
@@ -1797,7 +1797,7 @@ static int azx_pcm_hw_free(struct snd_pcm_substream *substream)
  	/* reset BDL address */
  	azx_sd_writel(azx_dev, SD_BDLPL, 0);
  	azx_sd_writel(azx_dev, SD_BDLPU, 0);
-	azx_sd_writel(azx_dev, SD_CTL, 0);
+	azx_stream_reset(chip, azx_dev);
  	azx_dev->bufsize = 0;
  	azx_dev->period_bytes = 0;
  	azx_dev->format_val = 0;

2.) we set 2 parameters in the .config file before kernel compiling


Both solutions didn´t work for us - still same problem. Has anyone 
another idea how to solve this?

Would be great if we could fix this.


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