From mboxrd@z Thu Jan 1 00:00:00 1970 From: Clemens Ladisch Subject: Re: SoC Atmel SSC stereo problem Date: Fri, 22 Oct 2010 18:11:57 +0200 Message-ID: <4CC1B7CD.3030703@ladisch.de> References: <4CC1AB01.3020603@fh-kl.de> 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 99A19103863 for ; Fri, 22 Oct 2010 18:10:07 +0200 (CEST) In-Reply-To: <4CC1AB01.3020603@fh-kl.de> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: alsa-devel-bounces@alsa-project.org Errors-To: alsa-devel-bounces@alsa-project.org To: Patrick Ziegler Cc: alsa-devel@alsa-project.org List-Id: alsa-devel@alsa-project.org Patrick Ziegler wrote: > I have some trouble with stereo audio through the atmal ssc interface > based on at91-ssc.c. (Merged into atmel_ssc_dai.c since about one year ago.) > Unfortunately left and right channels were swapped periodically. > > In my environment the codec supplies the BLCK and LRC clocks and > the SSC is configured to transmit one sample on both edges of the LRC clock. > But I guess the audio frames will always start with a frame of the left channel > while the LRC clock is in an undefined state. Indeed. > How does normally the audio driver detect when a left and when a right channel > frame should be send and with which it should start ? The driver cannot do anything about this; the hardware must be told to start transmitting at the falling edge. If possible. Is there a reason why the codec supplies LRC? Regards, Clemens