From mboxrd@z Thu Jan 1 00:00:00 1970 From: Clemens Ladisch Subject: Re: Delay calculations for USB audio? Date: Fri, 28 Sep 2012 14:30:50 +0200 Message-ID: <5065987A.1080703@ladisch.de> References: <5065834E.4010707@canonical.com> <506588A2.4070602@gmail.com> <5065907C.8030904@canonical.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from out1-smtp.messagingengine.com (out1-smtp.messagingengine.com [66.111.4.25]) by alsa0.perex.cz (Postfix) with ESMTP id EF3DE264F22 for ; Fri, 28 Sep 2012 14:30:52 +0200 (CEST) In-Reply-To: <5065907C.8030904@canonical.com> 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: David Henningsson Cc: alsa-devel@alsa-project.org, "Gabriel M. Beddingfield" List-Id: alsa-devel@alsa-project.org David Henningsson wrote: > On 09/28/2012 01:23 PM, Gabriel M. Beddingfield wrote: >> On 09/28/2012 06:00 AM, David Henningsson wrote: >>> * Selecting the outer USB port instead of the inner one. Yes, there >>> are two USB ports next to each other, and this only happens on one of >>> them. (!)) >> >> The last statement sounds like you're sharing a hub with another device >> that has reserved bandwidth. For example, a USB webcam will often do >> this. Audio will work for a while and then get pre-empted. For A/V devices, USB bandwidth is reserved in advance; it is not possible to have other device interfere (as long as the controller driver is written correctly ...). > Thanks! Indeed, when deactivating bluetooth (in both kernel 3.2 and 3.5) > the sound is back to normal I'd guess that that particular USB port and the bluetooth controller share an interrupt. > is it actually fixable if we wrote better drivers? Apparently, yes. Regards, Clemens