[08/26] ALSA: usb-audio - Check the dB-range validity in the later read, too

[Greg KH <gregkh@suse.de>]

3.0-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Takashi Iwai <tiwai@suse.de>

commit 9fcd0ab130579d9742538340edda3225f2b49a3e upstream.

When the initial check of dB-range failed due to the read error, try to
check again at the later read, too.  When an invalid dB range is found,
remove TLV flags and notify the mixer info change.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 sound/usb/mixer.c |   13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -881,8 +881,17 @@ static int mixer_ctl_feature_info(struct
 		uinfo->value.integer.min = 0;
 		uinfo->value.integer.max = 1;
 	} else {
-		if (! cval->initialized)
-			get_min_max(cval,  0);
+		if (!cval->initialized) {
+			get_min_max(cval, 0);
+			if (cval->initialized && cval->dBmin >= cval->dBmax) {
+				kcontrol->vd[0].access &=
+					~(SNDRV_CTL_ELEM_ACCESS_TLV_READ |
+					  SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK);
+				snd_ctl_notify(cval->mixer->chip->card,
+					       SNDRV_CTL_EVENT_MASK_INFO,
+					       &kcontrol->id);
+			}
+		}
 		uinfo->value.integer.min = 0;
 		uinfo->value.integer.max =
 			(cval->max - cval->min + cval->res - 1) / cval->res;