[alsa-devel] [PATCH] ALSA: usb-audio: set the interface format after resume on Dell WD19

[Takashi Iwai]

On Wed, 18 Dec 2019 14:26:50 +0100,
Hui Wang wrote:
> 
> Recently we found the headset-mic on the Dell Dock WD19 doesn't work
> anymore after s3 (s2i or deep), this problem could be workarounded by
> closeing (pcm_close) the app and then reopening (pcm_open) the app, so
> this bug is not easy to be detected by users.
> 
> When problem happens, retire_capture_urb() could still be called
> periodically, but the size of captured data is always 0, it could be
> a firmware bug on the dock. Anyway I found after resuming, the
> snd_usb_pcm_prepare() will be called, and if we forcibly run
> set_format() to set the interface and its endpoint, the capture
> size will be normal again. This problem and workaound also apply to
> playback.
> 
> To fix it in the kernel, add a quirk to let set_format() run
> forcibly once after resume.
> 
> Signed-off-by: Hui Wang <hui.wang at canonical.com>

Thanks, the workaround looks reasonable.
I applied it now with Cc to stable.


Takashi