[PATCH] ALSA: usb: Add Plantronics C320-M USB ctrl msg delay quirk

[John Ernberg]

The microphone in the Plantronics C320-M headset will randomly
fail to initialize properly, at least when using Microsoft Teams.
Introducing a 20ms delay on the control messages appears to
resolve the issue.

Link: https://gitlab.freedesktop.org/pulseaudio/pulseaudio/-/issues/1065
Tested-by: Andreas Kempe <kempe@xxxxxxxxxxxxxx>
Signed-off-by: John Ernberg <john.ernberg@xxxxxxxx>
---

Note: Microsoft Teams is the only application tests have been performed with
and no other kinds of investigations have been performed, like USB packet logging.
Originally reported as a possible PulseAudio issue, where it was suggested to
try a delay quirk in the kernel.
If other tests should be performed, please let me know which tests and I will try to do them.

All testing was done on 5.10, patch was then applied on sound.git master for submission

I did not register to the mailing lists, please keep me CC on any comments. Thanks!

 sound/usb/quirks.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/sound/usb/quirks.c b/sound/usb/quirks.c
index d02dac5fcd40..a31b7db92b1e 100644
--- a/sound/usb/quirks.c
+++ b/sound/usb/quirks.c
@@ -1673,6 +1673,14 @@ void snd_usb_ctl_msg_quirk(struct usb_device *dev, unsigned int pipe,
 	    && (requesttype & USB_TYPE_MASK) == USB_TYPE_CLASS)
 		msleep(20);
 
+	/*
+	 * Plantronics C320-M needs a delay to avoid random
+	 * microhpone failures.
+	 */
+	if (chip->usb_id == USB_ID(0x047f, 0xc025)  &&
+	    (requesttype & USB_TYPE_MASK) == USB_TYPE_CLASS)
+		msleep(20);
+
 	/* Zoom R16/24, many Logitech(at least H650e/H570e/BCC950),
 	 * Jabra 550a, Kingston HyperX needs a tiny delay here,
 	 * otherwise requests like get/set frequency return
-- 
2.30.0