ALSA: hda: Fix 0 dB offset for Lenovo Thinkpad models using AD1981

BugLink: https://launchpad.net/bugs/551606
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: <stable@kernel.org>
Signed-off-by: Daniel T Chen <crimsun@ubuntu.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/pci/hda/patch_analog.c b/sound/pci/hda/patch_analog.c
index e6d1bdf..af34606 100644 (file)
--- a/sound/pci/hda/patch_analog.c
+++ b/sound/pci/hda/patch_analog.c
@@ -1896,6 +1896,14 @@ 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;