From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id ED519C433DF for ; Wed, 12 Aug 2020 14:55:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C9BA422B4B for ; Wed, 12 Aug 2020 14:55:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726557AbgHLOzc (ORCPT ); Wed, 12 Aug 2020 10:55:32 -0400 Received: from mx2.suse.de ([195.135.220.15]:36678 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726447AbgHLOzb (ORCPT ); Wed, 12 Aug 2020 10:55:31 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 2CD5CAC1C; Wed, 12 Aug 2020 14:55:51 +0000 (UTC) Date: Wed, 12 Aug 2020 16:55:29 +0200 Message-ID: From: Takashi Iwai To: Pierre-Louis Bossart Cc: Yu-Hsuan Hsu , Guennadi Liakhovetski , "alsa-devel@alsa-project.org" , Andy Shevchenko , Kuninori Morimoto , Kai Vehmanen , "linux-kernel@vger.kernel.org" , "Rojewski, Cezary" , Jie Yang , Takashi Iwai , Liam Girdwood , Sam McNally , Mark Brown , Ranjani Sridharan , Daniel Stuart , "yuhsuan@google.com" , "Lu, Brent" , Damian van Soelen Subject: Re: [PATCH v3 2/2] ASoC: Intel: Add period size constraint on strago board In-Reply-To: References: <3f3baf5e-f73d-9cd6-cbfb-36746071e126@linux.intel.com> <20200811145353.GG6967@sirena.org.uk> <20200811172209.GM6967@sirena.org.uk> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI/1.14.6 (Maruoka) FLIM/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL/10.8 Emacs/25.3 (x86_64-suse-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 12 Aug 2020 16:46:40 +0200, Pierre-Louis Bossart wrote: > > > >>>>>> After doing some experiments, I think I can identify the problem more precisely. > >>>>>> 1. aplay can not reproduce this issue because it writes samples > >>>>>> immediately when there are some space in the buffer. However, you can > >>>>>> add --test-position to see how the delay grows with period size 256. > >>>>>>> aplay -Dhw:1,0 --period-size=256 --buffer-size=480 /dev/zero -d 1 -f dat --test-position > >>>>>> Playing raw data '/dev/zero' : Signed 16 bit Little Endian, Rate 48000 > >>>>>> Hz, Stereo > >>>>>> Suspicious buffer position (1 total): avail = 0, delay = 2064, buffer = 512 > >>>>>> Suspicious buffer position (2 total): avail = 0, delay = 2064, buffer = 512 > >>>>>> Suspicious buffer position (3 total): avail = 0, delay = 2096, buffer = 512 > >>>>>> ... > >>>>> > >>>>> Isn't this about the alignment of the buffer size against the period > >>>>> size, not the period size itself? i.e. in the example above, the > >>>>> buffer size isn't a multiple of period size, and DSP can't handle if > >>>>> the position overlaps the buffer size in a half way. > >>>>> > >>>>> If that's the problem (and it's an oft-seen restriction), the right > >>>>> constraint is > >>>>> snd_pcm_hw_constraint_integer(runtime, SNDRV_PCM_HW_PARAM_PERIODS); > >>>>> > >>>>> > >>>>> Takashi > >>>> Oh sorry for my typo. The issue happens no matter what buffer size is > >>>> set. Actually, even if I want to set 480, it will change to 512 > >>>> automatically. > >>>> Suspicious buffer position (1 total): avail = 0, delay = 2064, buffer > >>>> = 512 <-this one is the buffer size > >>> > >>> OK, then it means that the buffer size alignment is already in place. > >>> > >>> And this large delay won't happen if you use period size 240? > >>> > >>> > >>> Takashi > >> Yes! If I set the period size to 240, it will not print "Suspicious > >> buffer position ..." > > > > So it sounds like DSP handles the delay report incorrectly. > > Then it comes to another question: the driver supports both SOF and > > SST. Is there the behavior difference between both DSPs wrt this > > delay issue? > > I still don't get what the issue is. The two following cases work fine > with the SST/Atom driver: > > root@chrx:~# aplay -Dhw:0,0 --period-size=240 --buffer-size=480 > /dev/zero -d 2 -f dat --test-position > Playing raw data '/dev/zero' : Signed 16 bit Little Endian, Rate 48000 > Hz, Stereo > root@chrx:~# aplay -Dhw:0,0 --period-size=960 --buffer-size=4800 > /dev/zero -d 2 -f dat --test-position > Playing raw data '/dev/zero' : Signed 16 bit Little Endian, Rate 48000 > Hz, Stereo What if with --period-size=256 --buffer-size=512 and --test-position? Can you reproduce the problem in your side? > The existing code has this: > > /* Make sure, that the period size is always even */ > snd_pcm_hw_constraint_step(substream->runtime, 0, > SNDRV_PCM_HW_PARAM_PERIODS, 2); > > return snd_pcm_hw_constraint_integer(runtime, > SNDRV_PCM_HW_PARAM_PERIODS); > > and with the addition of period size being a multiple of 1ms all > requirements should be met? I also wonder what's really missing, too :) BTW, I took a look back at the thread, and CRAS seems using a very large buffer, namely: [ 52.434791] sound pcmC1D0p: PERIOD_SIZE [240:240] [ 52.434802] sound pcmC1D0p: BUFFER_SIZE [204480:204480] Takashi