ALSA: hda - Treat stereo-to-mono mix properly

The commit [ef403edb7558: ALSA: hda - Don't access stereo amps for
mono channel widgets] fixed the handling of mono widgets in general,
but it still misses an exceptional case: namely, a mono mixer widget
taking a single stereo input.  In this case, it has stereo volumes
although it's a mono widget, and thus we have to take care of both
left and right input channels, as stated in HD-audio spec ("7.1.3
Widget Interconnection Rules").

This patch covers this missing piece by adding proper checks of stereo
amps in both the generic parser and the proc output codes.

Reported-by: Raymond Yau <superquad.vortex2@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 19 insertions, 2 deletions

diff --git a/sound/pci/hda/hda_generic.c b/sound/pci/hda/hda_generic.c
index fe18071bf93a..8ec5289f8e05 100644
--- a/sound/pci/hda/hda_generic.c
+++ b/sound/pci/hda/hda_generic.c
@@ -687,13 +687,30 @@ static int get_amp_val_to_activate(struct hda_codec *codec, hda_nid_t nid,
         return val;
 }
 
+/* is this a stereo widget or a stereo-to-mono mix? */
+static bool is_stereo_amps(struct hda_codec *codec, hda_nid_t nid, int dir)
+{
+        unsigned int wcaps = get_wcaps(codec, nid);
+        hda_nid_t conn;
+
+        if (wcaps & AC_WCAP_STEREO)
+                return true;
+        if (dir != HDA_INPUT || get_wcaps_type(wcaps) != AC_WID_AUD_MIX)
+                return false;
+        if (snd_hda_get_num_conns(codec, nid) != 1)
+                return false;
+        if (snd_hda_get_connections(codec, nid, &conn, 1) < 0)
+                return false;
+        return !!(get_wcaps(codec, conn) & AC_WCAP_STEREO);
+}
+
 /* initialize the amp value (only at the first time) */
 static void init_amp(struct hda_codec *codec, hda_nid_t nid, int dir, int idx)
 {
         unsigned int caps = query_amp_caps(codec, nid, dir);
         int val = get_amp_val_to_activate(codec, nid, dir, caps, false);
 
-        if (get_wcaps(codec, nid) & AC_WCAP_STEREO)
+        if (is_stereo_amps(codec, nid, dir))
                 snd_hda_codec_amp_init_stereo(codec, nid, dir, idx, 0xff, val);
         else
                 snd_hda_codec_amp_init(codec, nid, 0, dir, idx, 0xff, val);
@@ -703,7 +720,7 @@ static void init_amp(struct hda_codec *codec, hda_nid_t nid, int dir, int idx)
 static int update_amp(struct hda_codec *codec, hda_nid_t nid, int dir, int idx,
                       unsigned int mask, unsigned int val)
 {
-        if (get_wcaps(codec, nid) & AC_WCAP_STEREO)
+        if (is_stereo_amps(codec, nid, dir))
                 return snd_hda_codec_amp_stereo(codec, nid, dir, idx,
                                                 mask, val);
         else