From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753374AbcHPJdg (ORCPT ); Tue, 16 Aug 2016 05:33:36 -0400 Received: from dehamd003.servertools24.de ([31.47.254.18]:55395 "EHLO dehamd003.servertools24.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751950AbcHPJdC (ORCPT ); Tue, 16 Aug 2016 05:33:02 -0400 Subject: Re: [PATCH v2 0/3] USB Audio Gadget refactoring To: Peter Chen , Ruslan Bilovol References: <1471126884-20117-1-git-send-email-ruslan.bilovol@gmail.com> <20160816091611.GA25819@shlinux2> Cc: Felipe Balbi , Daniel Mack , Jassi Brar , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org From: Clemens Ladisch Message-ID: Date: Tue, 16 Aug 2016 11:32:55 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 MIME-Version: 1.0 In-Reply-To: <20160816091611.GA25819@shlinux2> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-PPP-Message-ID: <20160816093259.866898.91856@dehamd003.servertools24.de> X-PPP-Vhost: ladisch.de Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Peter Chen wrote: > I find UAC2 (UAC1 is ok) support is not well with the latest mainline > kernel w/o your patch set. The windows7 can't install the driver > successfully Windows does not have UAC2 support. > and the playback shows underrun (using local codec) > using Linux host. > # arecord -f dat -t wav -D hw:1,0 | aplay -D hw:0,0 & The clocks of the two devices are not synchronized. In the ALSA API, a PCM device is assumed to have its own clock, so it is not possible to synchronize the USB gadget to the actual sound device without some separate mechanism (like the old uac1 gadget probably has). Regards, Clemens