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From: Takashi Iwai <>
To: Robert Giaraffa <>
Cc: "" <>,
	Daniel Mack <>
Subject: Re: [EXT] Re: Simultaneous play/record on implicit feedback device causes 'endpoint in use' error
Date: Fri, 02 Nov 2018 16:57:15 +0100
Message-ID: <> (raw)
In-Reply-To: <>

On Wed, 31 Oct 2018 20:45:07 +0100,
Robert Giaraffa wrote:
> Thank you very much for your prompt response.
> I tested the CP2615 and Fast Track Ultra by running aplay and arecord
> sequentially on my RPi2 v4.14.72 (with patched snd-usb-audio.ko that includes
> implicit feedback quirk for CP2615).  Although there were minor differences in
> the system logs for the two devices (e.g. ‘cannot submit urb’), but otherwise
> both devices behaved the same: whichever operation is started last resulted in
> the 'Endpoint already in use' error, regardless of sequence.  Detailed info
> below:

OK, so we obviously don't support the full duplex in this mode.

As a first step, could you try the simple patch below, and test in a
sequence record -> playback?  At least it should skip the check, and
proceed further.



--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -639,6 +639,10 @@ static int configure_sync_endpoint(struct snd_usb_substream *subs)
+	if (subs->sync_endpoint->type == SND_USB_ENDPOINT_TYPE_DATA &&
+	    subs->sync_endpoint->use_count)
+		return 0;
 	/* Try to find the best matching audioformat. */
 	list_for_each_entry(fp, &sync_subs->fmt_list, list) {
 		int score = match_endpoint_audioformats(subs,
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Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-30 23:15 Robert Giaraffa
2018-10-31 11:57 ` Takashi Iwai
2018-10-31 19:45   ` [EXT] " Robert Giaraffa
2018-11-02 15:57     ` Takashi Iwai [this message]
2020-01-15 15:33       ` [alsa-devel] " Alexander Tsoy

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