Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752817AbcD2DpT (ORCPT ); Thu, 28 Apr 2016 23:45:19 -0400 Received: from mail-ig0-f172.google.com ([209.85.213.172]:35416 "EHLO mail-ig0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752225AbcD2DpS (ORCPT ); Thu, 28 Apr 2016 23:45:18 -0400 Date: Thu, 28 Apr 2016 20:45:02 -0700 From: Nicolin Chen To: Caleb Crome Cc: Timur Tabi , Xiubo Li , Liam Girdwood , Mark Brown , Jaroslav Kysela , Takashi Iwai , alsa-devel@alsa-project.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 1/1] ASoC: fsl_ssi: add CCSR_SSI_SOR to volatile register list Message-ID: <20160429034502.GA1944@Asurada> References: <1461609378-467-1-git-send-email-caleb@crome.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1461609378-467-1-git-send-email-caleb@crome.org> User-Agent: Mutt/1.5.22 (2013-10-16) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1564 Lines: 44 On Mon, Apr 25, 2016 at 11:36:18AM -0700, Caleb Crome wrote: > The CCSR_SSI_SOR is a register that clears the TX and/or the RX fifo > on the i.MX SSI port. The fsl_ssi_trigger writes this register in > order to clear the fifo at trigger time. > > However, since the CCSR_SSI_SOR register is not in the volatile list, > the caching mechanism prevented the register write in the trigger > function. This caused the fifo to not be cleared (because the value > was unchanged from the last time the register was written), and thus > causes the channels in both TDM or simple I2S mode to slip and be in > the wrong time slots on SSI restart. > > This has gone unnoticed for so long because with simple stereo mode, > the consequence is that left and right are swapped, which isn't that > noticeable. However, it's catestrophic in some systems that > require the channels to be in the right slots. > > Signed-off-by: Caleb Crome > Suggested-by: Arnaud Mouiche Acked-by: Nicolin Chen Thanks > > --- > sound/soc/fsl/fsl_ssi.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/sound/soc/fsl/fsl_ssi.c b/sound/soc/fsl/fsl_ssi.c > index 216e3cb..2f3bf9c 100644 > --- a/sound/soc/fsl/fsl_ssi.c > +++ b/sound/soc/fsl/fsl_ssi.c > @@ -151,6 +151,7 @@ static bool fsl_ssi_volatile_reg(struct device *dev, unsigned int reg) > case CCSR_SSI_SACDAT: > case CCSR_SSI_SATAG: > case CCSR_SSI_SACCST: > + case CCSR_SSI_SOR: > return true; > default: > return false; > -- > 1.9.1 >