[PATCH] ALSA: usb-audio: Add mic resolution quirk for Logitech Webcam C200

[PATCH] ALSA: usb-audio: Add mic resolution quirk for Logitech Webcam C200

[Olivier Kaloudoff]

The C200 (046d:0802) reports a mic capture volume range of
1536..7680 with a resolution of 1 (6144 steps), triggering
"Warning! Unlikely big volume step count (=6144), linear volume or
wrong cval->res?" at probe and exposing a uselessly fine-grained
mixer control.  This is the same firmware behavior as the other
UVC-era Logitech webcams already carrying QUIRK_FLAG_MIC_RES_384
(C500, C600, C210, C270, C310, C510, C525, ...), so apply the same
quirk: CTL_MSG_DELAY_1M (which the Logitech VENDOR_FLG would provide
if the device-specific entry did not short-circuit the lookup) plus
MIC_RES_384.

Verified on real hardware: with the quirk the warning disappears and
the driver logs "set resolution quirk: cval->res = 384".

Signed-off-by: Olivier Kaloudoff <olivier.kaloudoff@gmail.com>
Cc: stable@vger.kernel.org
---
 sound/usb/quirks.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/sound/usb/quirks.c b/sound/usb/quirks.c
index c5870901a..16cb57f2c 100644
--- a/sound/usb/quirks.c
+++ b/sound/usb/quirks.c
@@ -2249,6 +2249,8 @@ static const struct usb_audio_quirk_flags_table quirk_flags_table[] = {
 		   QUIRK_FLAG_DISABLE_AUTOSUSPEND),
 	DEVICE_FLG(0x045e, 0x070f, /* MS LifeChat LX-3000 Headset */
 		   QUIRK_FLAG_MIXER_PLAYBACK_MIN_MUTE),
+	DEVICE_FLG(0x046d, 0x0802, /* Logitech Webcam C200 */
+		   QUIRK_FLAG_CTL_MSG_DELAY_1M | QUIRK_FLAG_MIC_RES_384),
 	DEVICE_FLG(0x046d, 0x0807, /* Logitech Webcam C500 */
 		   QUIRK_FLAG_CTL_MSG_DELAY_1M | QUIRK_FLAG_MIC_RES_384),
 	DEVICE_FLG(0x046d, 0x0808, /* Logitech Webcam C600 */
-- 
2.47.3

Re: [PATCH] ALSA: usb-audio: Add mic resolution quirk for Logitech Webcam C200

[sashiko-bot]

> The C200 (046d:0802) reports a mic capture volume range of
> 1536..7680 with a resolution of 1 (6144 steps), triggering
> "Warning! Unlikely big volume step count (=6144), linear volume or
> wrong cval->res?" at probe and exposing a uselessly fine-grained
> mixer control.  This is the same firmware behavior as the other
> UVC-era Logitech webcams already carrying QUIRK_FLAG_MIC_RES_384
> (C500, C600, C210, C270, C310, C510, C525, ...), so apply the same
> quirk: CTL_MSG_DELAY_1M (which the Logitech VENDOR_FLG would provide
> if the device-specific entry did not short-circuit the lookup) plus
> MIC_RES_384.
> 
> Verified on real hardware: with the quirk the warning disappears and
> the driver logs "set resolution quirk: cval->res = 384".
> 
> Signed-off-by: Olivier Kaloudoff <olivier.kaloudoff@gmail.com>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261008230844.11246-1-olivier.kaloudoff@gmail.com?part=1

Re: [PATCH] ALSA: usb-audio: Add mic resolution quirk for Logitech Webcam C200

[Takashi Iwai]

On Fri, 09 Oct 2026 01:08:44 +0200,
Olivier Kaloudoff wrote:
> 
> The C200 (046d:0802) reports a mic capture volume range of
> 1536..7680 with a resolution of 1 (6144 steps), triggering
> "Warning! Unlikely big volume step count (=6144), linear volume or
> wrong cval->res?" at probe and exposing a uselessly fine-grained
> mixer control.  This is the same firmware behavior as the other
> UVC-era Logitech webcams already carrying QUIRK_FLAG_MIC_RES_384
> (C500, C600, C210, C270, C310, C510, C525, ...), so apply the same
> quirk: CTL_MSG_DELAY_1M (which the Logitech VENDOR_FLG would provide
> if the device-specific entry did not short-circuit the lookup) plus
> MIC_RES_384.
> 
> Verified on real hardware: with the quirk the warning disappears and
> the driver logs "set resolution quirk: cval->res = 384".
> 
> Signed-off-by: Olivier Kaloudoff <olivier.kaloudoff@gmail.com>
> Cc: stable@vger.kernel.org

Applied to for-next branch now.  Thanks.


Takashi