This is a note to let you know that I've just added the patch titled ALSA: usb-audio: Add mute TLV for playback volumes on C-Media devices to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: alsa-usb-audio-add-mute-tlv-for-playback-volumes-on-c-media-devices.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 0f174b3525a43bd51f9397394763925e0ebe7bc7 Mon Sep 17 00:00:00 2001 From: Takashi Iwai <tiwai@xxxxxxx> Date: Wed, 16 Aug 2017 14:18:37 +0200 Subject: ALSA: usb-audio: Add mute TLV for playback volumes on C-Media devices From: Takashi Iwai <tiwai@xxxxxxx> commit 0f174b3525a43bd51f9397394763925e0ebe7bc7 upstream. C-Media devices (at least some models) mute the playback stream when volumes are set to the minimum value. But this isn't informed via TLV and the user-space, typically PulseAudio, gets confused as if it's still played in a low volume. This patch adds the new flag, min_mute, to struct usb_mixer_elem_info for indicating that the mixer element is with the minimum-mute volume. This flag is set for known C-Media devices in snd_usb_mixer_fu_apply_quirk() in turn. Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=196669 Signed-off-by: Takashi Iwai <tiwai@xxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- sound/usb/mixer.c | 2 ++ sound/usb/mixer.h | 1 + sound/usb/mixer_quirks.c | 6 ++++++ 3 files changed, 9 insertions(+) --- a/sound/usb/mixer.c +++ b/sound/usb/mixer.c @@ -542,6 +542,8 @@ int snd_usb_mixer_vol_tlv(struct snd_kco if (size < sizeof(scale)) return -ENOMEM; + if (cval->min_mute) + scale[0] = SNDRV_CTL_TLVT_DB_MINMAX_MUTE; scale[2] = cval->dBmin; scale[3] = cval->dBmax; if (copy_to_user(_tlv, scale, sizeof(scale))) --- a/sound/usb/mixer.h +++ b/sound/usb/mixer.h @@ -64,6 +64,7 @@ struct usb_mixer_elem_info { int cached; int cache_val[MAX_CHANNELS]; u8 initialized; + u8 min_mute; void *private_data; }; --- a/sound/usb/mixer_quirks.c +++ b/sound/usb/mixer_quirks.c @@ -1873,6 +1873,12 @@ void snd_usb_mixer_fu_apply_quirk(struct if (unitid == 7 && cval->control == UAC_FU_VOLUME) snd_dragonfly_quirk_db_scale(mixer, cval, kctl); break; + /* lowest playback value is muted on C-Media devices */ + case USB_ID(0x0d8c, 0x000c): + case USB_ID(0x0d8c, 0x0014): + if (strstr(kctl->id.name, "Playback")) + cval->min_mute = 1; + break; } } Patches currently in stable-queue which might be from tiwai@xxxxxxx are queue-4.9/alsa-seq-2nd-attempt-at-fixing-race-creating-a-queue.patch queue-4.9/alsa-usb-audio-apply-sample-rate-quirk-to-sennheiser-headset.patch queue-4.9/alsa-usb-audio-add-mute-tlv-for-playback-volumes-on-c-media-devices.patch