ALSA: hda - Add sanity check of vmaster slave dB steps

Check whether all vmaster slaves have the same dB steps.  Otherwise
the behavior would become inconsistent.

Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 12 insertions, 4 deletions

diff --git a/sound/pci/hda/hda_codec.c b/sound/pci/hda/hda_codec.c
index 33c01d551aa4..dd5403d40830 100644
--- a/sound/pci/hda/hda_codec.c
+++ b/sound/pci/hda/hda_codec.c
@@ -2661,7 +2661,7 @@ static int check_slave_present(void *data, struct snd_kcontrol *sctl)
 }
 
 /* guess the value corresponding to 0dB */
-static int get_kctl_0dB_offset(struct snd_kcontrol *kctl)
+static int get_kctl_0dB_offset(struct snd_kcontrol *kctl, int *step_to_check)
 {
         int _tlv[4];
         const int *tlv = NULL;
@@ -2681,6 +2681,12 @@ static int get_kctl_0dB_offset(struct snd_kcontrol *kctl)
                 step &= ~TLV_DB_SCALE_MUTE;
                 if (!step)
                         return -1;
+                if (*step_to_check && *step_to_check != step) {
+                        snd_printk(KERN_ERR "hda_codec: Mismatching dB step for vmaster slave (%d!=%d)\n",
+                                   *step_to_check, step);
+                        return -1;
+                }
+                *step_to_check = step;
                 val = -tlv[2] / step;
         }
         return val;
@@ -2703,7 +2709,7 @@ static int put_kctl_with_value(struct snd_kcontrol *kctl, int val)
 /* initialize the slave volume with 0dB */
 static int init_slave_0dB(void *data, struct snd_kcontrol *slave)
 {
-        int offset = get_kctl_0dB_offset(slave);
+        int offset = get_kctl_0dB_offset(slave, data);
         if (offset > 0)
                 put_kctl_with_value(slave, offset);
         return 0;
@@ -2764,9 +2770,11 @@ int __snd_hda_add_vmaster(struct hda_codec *codec, char *name,
 
         /* init with master mute & zero volume */
         put_kctl_with_value(kctl, 0);
-        if (init_slave_vol)
+        if (init_slave_vol) {
+                int step = 0;
                 map_slaves(codec, slaves, suffix,
-                           tlv ? init_slave_0dB : init_slave_unmute, kctl);
+                           tlv ? init_slave_0dB : init_slave_unmute, &step);
+        }
 
         if (ctl_ret)
                 *ctl_ret = kctl;