Comment 3 for bug 551606

From f3b52812102a1072a20346d6ea45929e60eab23b Mon Sep 17 00:00:00 2001
From: Daniel T Chen <email address hidden>
Date: Tue, 30 Mar 2010 13:29:28 -0400
Subject: [PATCH] ALSA: hda: Fix 0 dB offset for Lenovo Thinkpad models using AD1981

The OR's hardware distorts at PCM 100% because it does not correspond to
0 dB. Fix this in patch_ad1981() for all models using the Thinkpad
quirk.

Reported-by: Jane Silber
Cc: <email address hidden>
Signed-off-by: Daniel T Chen <email address hidden>
---
 sound/pci/hda/patch_analog.c | 8 ++++++++
 1 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/sound/pci/hda/patch_analog.c b/sound/pci/hda/patch_analog.c
index 262f5b5..9cbd80c 100644
--- a/sound/pci/hda/patch_analog.c
+++ b/sound/pci/hda/patch_analog.c
@@ -1904,6 +1904,14 @@ static int patch_ad1981(struct hda_codec *codec)
  case AD1981_THINKPAD:
   spec->mixers[0] = ad1981_thinkpad_mixers;
   spec->input_mux = &ad1981_thinkpad_capture_source;
+ /* set the upper-limit for mixer amp to 0dB for avoiding the
+ * possible damage by overloading
+ */
+ snd_hda_override_amp_caps(codec, 0x11, HDA_INPUT,
+ (0x17 << AC_AMPCAP_OFFSET_SHIFT) |
+ (0x17 << AC_AMPCAP_NUM_STEPS_SHIFT) |
+ (0x05 << AC_AMPCAP_STEP_SIZE_SHIFT) |
+ (1 << AC_AMPCAP_MUTE_SHIFT));
   break;
  case AD1981_TOSHIBA:
   spec->mixers[0] = ad1981_hp_mixers;
--
1.7.0