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From ec43e93b7e36e2baa6685da504b9db3ac7048ceb Mon Sep 17 00:00:00 2001
From: Jonathan Bell <jonathan@raspberrypi.com>
Date: Fri, 16 Apr 2021 11:40:23 +0100
Subject: [PATCH] sound/usb: call usb_autopm_get_interface() for
devices that should not be suspended
Webcams with microphones are composite devices, and autosuspend is set
at the device level. If uvcvideo is probed after snd-usb-audio, the effect
of the quirk applied by snd-usb-audio is undone by uvcvideo's global
application of autosuspend.
Incrementing the interface's PM refcount in such cases prevents runtime PM
from happening, thus the device is left active.
Signed-off-by: Jonathan Bell <jonathan@raspberrypi.com>
---
sound/usb/quirks.c | 5 +++++
1 file changed, 5 insertions(+)
--- a/sound/usb/quirks.c
+++ b/sound/usb/quirks.c
@@ -531,6 +531,11 @@ static int setup_disable_autosuspend(str
struct usb_driver *driver,
const struct snd_usb_audio_quirk *quirk)
{
+ /*
+ * Grab the interface, because on a webcam uvcvideo may race
+ * with snd-usb-audio during probe and re-enable autosuspend.
+ */
+ usb_autopm_get_interface(iface);
usb_disable_autosuspend(interface_to_usbdev(iface));
return 1; /* Continue with creating streams and mixer */
}
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