From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761343AbdACVJO (ORCPT ); Tue, 3 Jan 2017 16:09:14 -0500 Received: from mail-oi0-f67.google.com ([209.85.218.67]:34870 "EHLO mail-oi0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758658AbdACVIz (ORCPT ); Tue, 3 Jan 2017 16:08:55 -0500 MIME-Version: 1.0 In-Reply-To: <1483467777-8651-1-git-send-email-caleb@signalessence.com> References: <1483467777-8651-1-git-send-email-caleb@signalessence.com> From: Fabio Estevam Date: Tue, 3 Jan 2017 19:08:53 -0200 Message-ID: Subject: Re: [alsa-devel] [PATCH] fsl_ssi: set fifo watermark to more reliable value To: Caleb Crome Cc: Timur Tabi , Nicolin Chen , Xiubo Li , Fabio Estevam , Liam Girdwood , Mark Brown , Jaroslav Kysela , Takashi Iwai , "alsa-devel@alsa-project.org" , "linuxppc-dev@lists.ozlabs.org" , linux-kernel , Arnaud Mouiche , Caleb Crome Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 3, 2017 at 4:22 PM, Caleb Crome wrote: > From: Caleb Crome > > The fsl_ssi fifo watermark is by default set to 2 free spaces (i.e. > activate DMA on FIFO when only 2 spaces are left.) This means the > DMA must service the fifo within 2 audio samples, which is just not > enough time for many use cases with high data rate. In many > configurations the audio channel slips (causing l/r swap in stereo > configurations, or channel slipping in multi-channel configurations). > > This patch gives more breathing room and allows the SSI to operate > reliably by changing the fifio refill watermark to 8. > > There is no change in behavior for older chips (with an 8-deep fifo). > Only the newer chips with a 15-deep fifo get the new behavior. I > suspect a new fifo depth setting could be optimized on the older > chips too, but I have not tested. > > Signed-off-by: Caleb Crome Reviewed-by: Fabio Estevam