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=-5.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 AA0E3C433DF for ; Wed, 12 Aug 2020 14:46:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 88BC320838 for ; Wed, 12 Aug 2020 14:46:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726688AbgHLOqp (ORCPT ); Wed, 12 Aug 2020 10:46:45 -0400 Received: from mga02.intel.com ([134.134.136.20]:44428 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726485AbgHLOqp (ORCPT ); Wed, 12 Aug 2020 10:46:45 -0400 IronPort-SDR: TgRbw0C1BDKKoNjdba/I/l3aCUTBPALjXiVRUtaBZJwFIS19pbPznkQp7p0E1IODrDBlilwwD/ U+4V2jOZ7X+Q== X-IronPort-AV: E=McAfee;i="6000,8403,9711"; a="141808420" X-IronPort-AV: E=Sophos;i="5.76,304,1592895600"; d="scan'208";a="141808420" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Aug 2020 07:46:43 -0700 IronPort-SDR: o8Cq+YOgWp9qmw+FblQ9WE1g+XI0I+lCaQ85lcRakeBxWtHTZVHrRkPiUyBFVnvecIHwHDQV7P KVCXC9lOfGfw== X-IronPort-AV: E=Sophos;i="5.76,304,1592895600"; d="scan'208";a="469844036" Received: from rkiran1x-mobl1.amr.corp.intel.com (HELO [10.212.203.28]) ([10.212.203.28]) by orsmga005-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Aug 2020 07:46:42 -0700 Subject: Re: [PATCH v3 2/2] ASoC: Intel: Add period size constraint on strago board To: Takashi Iwai , Yu-Hsuan Hsu Cc: 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 References: <3f3baf5e-f73d-9cd6-cbfb-36746071e126@linux.intel.com> <20200811145353.GG6967@sirena.org.uk> <20200811172209.GM6967@sirena.org.uk> From: Pierre-Louis Bossart Message-ID: Date: Wed, 12 Aug 2020 09:46:40 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >>>>>> 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 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?