From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Keith A. Milner" Subject: Re: Attempting to understand odd snd-usb-audio code and behavior Date: Wed, 23 Aug 2017 12:25:03 +0100 Message-ID: <1954362.aJMGcWAYHc@kamdesktop> References: <2006820.TBXnYHJvYE@kamdesktop> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail-wm0-f52.google.com (mail-wm0-f52.google.com [74.125.82.52]) by alsa0.perex.cz (Postfix) with ESMTP id ABC6526735E for ; Wed, 23 Aug 2017 13:25:06 +0200 (CEST) Received: by mail-wm0-f52.google.com with SMTP id r187so13334942wma.0 for ; Wed, 23 Aug 2017 04:25:06 -0700 (PDT) Received: from kamdesktop.localnet (2.7.2.6.c.3.7.d.6.2.e.2.5.5.4.1.d.a.9.2.a.0.e.b.0.b.8.0.1.0.0.2.ip6.arpa. [2001:8b0:be0a:29ad:1455:2e26:d73c:6272]) by smtp.gmail.com with ESMTPSA id 65sm1323519wmf.0.2017.08.23.04.25.04 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 23 Aug 2017 04:25:04 -0700 (PDT) In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: alsa-devel-bounces@alsa-project.org Sender: alsa-devel-bounces@alsa-project.org To: alsa-devel@alsa-project.org List-Id: alsa-devel@alsa-project.org On Wednesday 23 Aug 2017 12:23:00 Clemens Ladisch wrote: > Keith A. Milner wrote: > > > > It seems to open and close the PCMs > > That happens due to requests from user space, probably PulseAudio. > > > kernel: [ 1987.452947] usb 1-1: Unable to change format on ep #8e: already > > in use > So this is a Roland device? Playback-synchronized-to-capture is a very > special case; at the moment, nobody understands this code completely. > > But the problem for this device might be that it requires some > vendor-specific messages to enable it in the first place. That's very useful, thank you. I forgot about pulseaudio! So the error messages are due to a userspace app trying to open playback and capture at the same time? Or is it just a generic driver/card issue when trying to open the interface? I have the ability to sniff the USB whilst running on Windows. For this specific device I may try that. Regards, Keith