From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Mack Subject: Re: [alsa-devel] channel swapping issue on OMAP3/TWL4030 is back Date: Fri, 22 Mar 2013 10:07:34 +0100 Message-ID: <514C1F56.7080403@gmail.com> References: <514C1C78.3090702@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from mail-wi0-f178.google.com ([209.85.212.178]:34289 "EHLO mail-wi0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932373Ab3CVJHf (ORCPT ); Fri, 22 Mar 2013 05:07:35 -0400 Received: by mail-wi0-f178.google.com with SMTP id hq4so4042939wib.17 for ; Fri, 22 Mar 2013 02:07:34 -0700 (PDT) In-Reply-To: Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Peter Meerwald Cc: Peter Ujfalusi , Jarkko Nikula , alsa-devel@alsa-project.org, linux-omap@vger.kernel.org On 22.03.2013 10:03, Peter Meerwald wrote: > >>> I'm running Linux 3.7 on a beagle-xm and observe very reproducible stereo >>> channel swapping issue on playback of a stereo stream (one channel has a >>> sine, the other is zero); the channel swap occurs on starting the playback > >> Always? Or in like 50% of the runs? And is the record stream (IOW: the >> clocks) already running when you switch on playback? > > in 10 runs, the swap can maybe observed 3 times; so: not always > > I can easily turn on/off the clock for the McBSP3/TLV320AIC3104 setup; > with McBSP3 being master I ONLY have the issue when the clock is already > running; when I start the stream first, then turn on the clock, there is > NO SWAP Yes, that sounds familiar. I guess the problem is that the serial line driver does not respect a specific slope (like lo->hi) but will sync up to *any* slope once it gets its enable bit set. Which will give you arbitrary channel swaps. Daniel