From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753951Ab0EKRcy (ORCPT ); Tue, 11 May 2010 13:32:54 -0400 Received: from mail-ew0-f216.google.com ([209.85.219.216]:41246 "EHLO mail-ew0-f216.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751056Ab0EKRcw (ORCPT ); Tue, 11 May 2010 13:32:52 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; b=UU4TOsHqNvjSGJ48Tz9y3K4OT1xZ5BgCYLBttsPz5NbC6nSxv4tILbGraKmTaFEknt QBUvP5xCU6Fqy50RlfxNU0tButXdDqmLyE1rl0A6ywV/DKHawoA+aJRirxc7qvMPZLgh kMmEC5+sivnPx+FbqmUtquqgGnDN/TUYGCACI= MIME-Version: 1.0 In-Reply-To: <20100511171025.GB30801@buzzloop.caiaq.de> References: <20100512003450P.fujita.tomonori@lab.ntt.co.jp> <20100511171025.GB30801@buzzloop.caiaq.de> Date: Tue, 11 May 2010 18:32:50 +0100 Message-ID: Subject: Re: [alsa-devel] USB transfer_buffer allocations on 64bit systems From: Pedro Ribeiro To: Daniel Mack Cc: Alan Stern , FUJITA Tomonori , gregkh@suse.de, konrad.wilk@oracle.com, tiwai@suse.de, USB list , clemens@ladisch.de, Kernel development list , chrisw@sous-sol.org, iommu@lists.linux-foundation.org, andi@firstfloor.org, Andrew Morton , dwmw2@infradead.org Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11 May 2010 18:10, Daniel Mack wrote: > On Tue, May 11, 2010 at 05:48:11PM +0100, Pedro Ribeiro wrote: >> I'm clueless about the whole underlying process but I don't think it >> is related to playing a file from the disk or another USB device. >> >> I don't need to play any file for this interference to be heard - I >> just need to "open" the device. By this I mean that if I create a JACK > > ... which will stream zeros. Sure, that should also trigger the bug > then. > >> server or if I open the device using the ALSA backed in a program like >> Mixxx I immediately start hearing the cracks and pops in the speaker. >> But to answer your question, playing a file from the hard drive using >> aplay I can also hear the interference - but only when the sound is >> playing. As soon as the sound stops and the audio device is "closed", >> no interference occurs. > > Yes, because the stream is stopped, pending URBs are unlinked etc. > That's completely expected. > >> However, when using the JACK server, which probably opens and polls >> the audio card constantly (its a low latency audio server) I don't >> even need to be playing any sound for the interference to be constant. > > That shouldn't affect the driver itself but just put the ALSA core under > pressure. > >> I can also see it since I have 4 output leds in the USB audio card and >> even if I'm only using 2 channels, the 4 channel leds light up with >> interference as the sound cracks and pops. > > No surprise here. The 4 channels are mux'ed in an interleaved fashion, > so if the buffers contain rubbish, you will hear artefacts on all > channels. > > Daniel > > So what would be the testcase you would like me to try? Pedro