when usb audio device removes, we need to stop the current pcm
substream when detecting hw disconnects. otherwise the read /
write thread may sleep for long time before timeout, thus upper
layer is blocked for long time and can't repsond quickly to the
hw disconnection.

also substream & pcm may still be used after audio unbind, and
we should only set null to it in audio_pcm_close.

Signed-off-by: Qiao Zhou <zhouq...@marvell.com>
---
 drivers/usb/gadget/f_audio_source.c |   11 +++++++++--
 1 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/gadget/f_audio_source.c 
b/drivers/usb/gadget/f_audio_source.c
index c757409..8d4f58e 100644
--- a/drivers/usb/gadget/f_audio_source.c
+++ b/drivers/usb/gadget/f_audio_source.c
@@ -620,15 +620,21 @@ static void
 audio_unbind(struct usb_configuration *c, struct usb_function *f)
 {
        struct audio_dev *audio = func_to_audio(f);
+       struct snd_pcm_substream *substream = audio->substream;
        struct usb_request *req;
 
        while ((req = audio_req_get(audio)))
                audio_request_free(req, audio->in_ep);
 
+       /* stop pcm stream when audio unbind after hw disconnect */
+       if (substream && substream->runtime && snd_pcm_running(substream)) {
+               snd_pcm_stream_lock_irq(substream);
+               snd_pcm_stop(substream, SNDRV_PCM_STATE_DISCONNECTED);
+               snd_pcm_stream_unlock_irq(substream);
+       }
+
        snd_card_free_when_closed(audio->card);
        audio->card = NULL;
-       audio->pcm = NULL;
-       audio->substream = NULL;
        audio->in_ep = NULL;
 }
 
@@ -670,6 +676,7 @@ static int audio_pcm_close(struct snd_pcm_substream 
*substream)
        unsigned long flags;
 
        spin_lock_irqsave(&audio->lock, flags);
+       audio->pcm = NULL;
        audio->substream = NULL;
        spin_unlock_irqrestore(&audio->lock, flags);
 
-- 
1.7.0.4

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