From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Pierre C" Subject: USB Implicit Feedback Date: Sat, 06 Sep 2014 08:53:23 +0200 Message-ID: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed"; DelSp="yes" Content-Transfer-Encoding: 7bit Return-path: Received: from mo68.mail-out.ovh.net (9.mo68.mail-out.ovh.net [46.105.78.111]) by alsa0.perex.cz (Postfix) with ESMTP id 0383B264F40 for ; Sat, 6 Sep 2014 08:53:26 +0200 (CEST) Received: from mail138.ha.ovh.net (b9.ovh.net [213.186.33.59]) by mo68.mail-out.ovh.net (Postfix) with SMTP id 981DBFF9528 for ; Sat, 6 Sep 2014 08:53:25 +0200 (CEST) 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 Hello ! I'm implementing a USB Audio Class 2 device using a Cortex-M4 with high speed USB. So far it works well, the device is recognized by ALSA, playback, capture, sample rate change, and all controls like volume and mute work. I'm using explicit feedback. I'd like to use implicit feedback instead, and had some problems... With implicit feedback, when playback starts, ALSA should start capture automatically (even if there are no applications requesting capture at the moment) to use the number of capture samples as feedback. But it doesn't. So, I'd like to know : - Is it actually supported ? - If it is, what descriptors should I use to make it work ? Thanks for any info, have a nice day ! Pierre