1 files changed, 16 insertions, 0 deletions

diff --git a/sound/pci/cs5535audio/cs5535audio_pcm.c b/sound/pci/cs5535audio/cs5535audio_pcm.c
index 6aa0c19390d7..fa2a6b1b81a6 100644
--- a/sound/pci/cs5535audio/cs5535audio_pcm.c
+++ b/sound/pci/cs5535audio/cs5535audio_pcm.c
@@ -363,11 +363,27 @@ static int snd_cs5535audio_capture_open(struct snd_pcm_substream *substream)
         if ((err = snd_pcm_hw_constraint_integer(runtime,
                                          SNDRV_PCM_HW_PARAM_PERIODS)) < 0)
                 return err;
+
+#ifdef CONFIG_OLPC
+        /* Enable the V_ref bias only while recording. */
+        err = snd_ac97_update_bits(cs5535au->ac97, AC97_AD_MISC,
+                        1 << AC97_AD_VREFD_SHIFT, 0);
+        if (err < 0)
+                snd_printk(KERN_ERR "Error updating AD_MISC %d\n", err);
+#endif
         return 0;
 }
 
 static int snd_cs5535audio_capture_close(struct snd_pcm_substream *substream)
 {
+        int err;
+        struct cs5535audio *cs5535au = snd_pcm_substream_chip(substream);
+
+#ifdef CONFIG_OLPC
+        /* Disable V_ref bias. */
+        err = snd_ac97_update_bits(cs5535au->ac97, AC97_AD_MISC,
+                        1 << AC97_AD_VREFD_SHIFT, 1 << AC97_AD_VREFD_SHIFT);
+#endif
         return 0;
 }