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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 1BC26C0044C for ; Mon, 5 Nov 2018 16:11:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 878D42081D for ; Mon, 5 Nov 2018 16:11:52 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 878D42081D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387504AbeKFBcO (ORCPT ); Mon, 5 Nov 2018 20:32:14 -0500 Received: from mx2.suse.de ([195.135.220.15]:48400 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729019AbeKFBcO (ORCPT ); Mon, 5 Nov 2018 20:32:14 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id C79C9B06C; Mon, 5 Nov 2018 16:11:48 +0000 (UTC) Date: Mon, 05 Nov 2018 17:11:47 +0100 Message-ID: From: Takashi Iwai To: Mike Brady Cc: Stefan Wahren , devel@driverdev.osuosl.org, alsa-devel@alsa-project.org, f.fainelli@gmail.com, julia.lawall@lip6.fr, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, eric@anholt.net, linux-rpi-kernel@lists.infradead.org, nishka.dasgupta_ug18@ashoka.edu.in, Kirill Marinushkin , linux-arm-kernel@lists.infradead.org Subject: Re: [alsa-devel] [PATCH v2] staging: bcm2835-audio: interpolate audio delay In-Reply-To: References: <20181022191708.GA4659@ubuntu> <046aea96-e0d3-60f4-c61a-c26bb1b5c193@gmail.com> <9884c4f5-2343-e3a4-8d8b-dd2db404ef27@gmail.com> <126FA055-050B-4AAC-9392-CA8CCA821768@eircom.net> 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/26 (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=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 05 Nov 2018 16:57:07 +0100, Mike Brady wrote: > > > One another thing I'd like to point out is that the value given in the > > patch is nothing but an estimated position, optimistically calculated > > via the system timer. Mike and I had already discussion in another > > thread, and another possible option would be to provide the proper > > timestamp-vs-hwptr pair, instead of updating the timestamp always at > > the status read. > > Agreed — that would give the caller the information needed to do the > interpolation for themselves if desired. And now I wonder whether the problem is still present with the latest code. There was a (kind of) regression in this regard when we introduced the fine-grained hardware timestamping, but it should have been addressed by the commit 20e3f985bb875fea4f86b04eba4b6cc29bfd6b71 ALSA: pcm: update tstamp only if audio_tstamp changed Could you double-check whether the tstamp field gets still updated even if no hwptr (and delay) is changed? thanks, Takashi From mboxrd@z Thu Jan 1 00:00:00 1970 From: tiwai@suse.de (Takashi Iwai) Date: Mon, 05 Nov 2018 17:11:47 +0100 Subject: [alsa-devel] [PATCH v2] staging: bcm2835-audio: interpolate audio delay In-Reply-To: References: <20181022191708.GA4659@ubuntu> <046aea96-e0d3-60f4-c61a-c26bb1b5c193@gmail.com> <9884c4f5-2343-e3a4-8d8b-dd2db404ef27@gmail.com> <126FA055-050B-4AAC-9392-CA8CCA821768@eircom.net> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Mon, 05 Nov 2018 16:57:07 +0100, Mike Brady wrote: > > > One another thing I'd like to point out is that the value given in the > > patch is nothing but an estimated position, optimistically calculated > > via the system timer. Mike and I had already discussion in another > > thread, and another possible option would be to provide the proper > > timestamp-vs-hwptr pair, instead of updating the timestamp always at > > the status read. > > Agreed ? that would give the caller the information needed to do the > interpolation for themselves if desired. And now I wonder whether the problem is still present with the latest code. There was a (kind of) regression in this regard when we introduced the fine-grained hardware timestamping, but it should have been addressed by the commit 20e3f985bb875fea4f86b04eba4b6cc29bfd6b71 ALSA: pcm: update tstamp only if audio_tstamp changed Could you double-check whether the tstamp field gets still updated even if no hwptr (and delay) is changed? thanks, Takashi