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From: Sasha Levin <sashal@kernel.org>
To: stable@vger.kernel.org
Cc: Olivier Kaloudoff <olivier.kaloudoff@gmail.com>,
	Takashi Iwai <tiwai@suse.de>, Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.10.y] ALSA: usb-audio: Add mic resolution quirk for Logitech Webcam C200
Date: Tue, 10 Nov 2026 11:04:35 -0500	[thread overview]
Message-ID: <20261110160421.2032791-1-sashal@kernel.org> (raw)
In-Reply-To: <20261107062007-failed-5.10-874323b68c93@kernel.org>

From: Olivier Kaloudoff <olivier.kaloudoff@gmail.com>

[ Upstream commit 874323b68c93c6808e034dc0113681e822e6fb42 ]

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
Link: https://patch.msgid.link/20261008230844.11246-1-olivier.kaloudoff@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
[ sashal: Replaced the quirk flag table entry with a USB_ID case in volume_control_quirks(). ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 sound/usb/mixer.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index 7f64199139d31..48178272bf422 100644
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -1163,6 +1163,7 @@ static void volume_control_quirks(struct usb_mixer_elem_info *cval,
 		}
 		break;
 
+	case USB_ID(0x046d, 0x0802): /* Logitech Webcam C200 */
 	case USB_ID(0x046d, 0x0807): /* Logitech Webcam C500 */
 	case USB_ID(0x046d, 0x0808):
 	case USB_ID(0x046d, 0x0809):
-- 
2.53.0


      reply	other threads:[~2026-11-10 16:04 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-11-07 11:20 FAILED: patch "[PATCH] ALSA: usb-audio: Add mic resolution quirk for Logitech Webcam C200" failed to apply to 5.10-stable tree Sasha Levin
2026-11-10 16:04 ` Sasha Levin [this message]

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