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=-3.7 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 3141EC433E0 for ; Thu, 9 Jul 2020 11:03:46 +0000 (UTC) Received: from alsa0.perex.cz (alsa0.perex.cz [77.48.224.243]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id B43892076A for ; Thu, 9 Jul 2020 11:03:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alsa-project.org header.i=@alsa-project.org header.b="kVau/xRU" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B43892076A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=alsa-devel-bounces@alsa-project.org Received: from alsa1.perex.cz (alsa1.perex.cz [207.180.221.201]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by alsa0.perex.cz (Postfix) with ESMTPS id 51F5615E0; Thu, 9 Jul 2020 13:02:54 +0200 (CEST) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa0.perex.cz 51F5615E0 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=alsa-project.org; s=default; t=1594292624; bh=QRmRFJKNb/XOIrGcr6OLXsxae3IPgZtT2k4SGjH79XI=; h=Date:From:To:Subject:In-Reply-To:References:Cc:List-Id: List-Unsubscribe:List-Archive:List-Post:List-Help:List-Subscribe: From; b=kVau/xRUO1Kr+pkE7JpqMehz/woH3kkVIMIwSJF1CXHhB521oNu2z7Mhu/Ilk9zW5 SpwYZXsshZtYqovz69OIuRac70ym3soaql4l/hM01YANXjtctDHwyGYvTfAe/zmsbS fSuxC5KvqCl6oT1DzQ3WMNT60h6kmato+VlUV16E= Received: from alsa1.perex.cz (localhost.localdomain [127.0.0.1]) by alsa1.perex.cz (Postfix) with ESMTP id 58225F80257; Thu, 9 Jul 2020 13:01:15 +0200 (CEST) Received: by alsa1.perex.cz (Postfix, from userid 50401) id C89EFF80257; Thu, 9 Jul 2020 13:01:13 +0200 (CEST) Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by alsa1.perex.cz (Postfix) with ESMTPS id 8B486F80257 for ; Thu, 9 Jul 2020 13:01:07 +0200 (CEST) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa1.perex.cz 8B486F80257 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 D423EAE2D; Thu, 9 Jul 2020 11:01:06 +0000 (UTC) Date: Thu, 09 Jul 2020 13:01:07 +0200 Message-ID: From: Takashi Iwai To: Mark Hills Subject: Re: [PATCH 5/5] echoaudio: Address bugs in the interrupt handling In-Reply-To: <20200708101848.3457-5-mark@xwax.org> References: <2007081115280.3085@stax.localdomain> <20200708101848.3457-5-mark@xwax.org> 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 Cc: alsa-devel@alsa-project.org X-BeenThere: alsa-devel@alsa-project.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: "Alsa-devel mailing list for ALSA developers - http://www.alsa-project.org" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: alsa-devel-bounces@alsa-project.org Sender: "Alsa-devel" On Wed, 08 Jul 2020 12:18:48 +0200, Mark Hills wrote: > > Distorted audio appears occasionally, affecting either playback or > capture and requiring the affected substream to be closed by all > applications and re-opened. > > The best way I have found to reproduce the bug is to use dmix in > combination with Chromium, which opens the audio device multiple times > in threads. Anecdotally, the problems appear to have increased with > faster CPUs. I ruled out 32-bit counter wrapping; it often happens > much earlier. > > Since applying this patch I have not had problems, where previously > they would occur several times a day. > > The patch targets the following issues: > > * Check for progress using the counter from the hardware, not after it > has been truncated to the buffer. > > This is a clean way to address a possible bug where if a whole > ringbuffer advances between interrupts, it goes unnoticed. > > * Move last_period state from chip to pipe > > This more logically belongs as part of pipe, and code is reasier to > read if it is "counter position last time a period elapsed". > > Now the code has no references to period count. A period is just > when the regular counter crosses a threshold. This increases > readability and reduces scope for bugs. > > * Treat period notification and buffer advance independently: > > This helps to clarify what is the responsibility of the interrupt > handler, and what is pcm_pointer(). > > Removing shared state between these operations means race conditions > are fixed without introducing locks. Synchronisation is only around > the read of pipe->dma_counter. There may be cache line contention > around "struct audiopipe" but I did not have cause to profile this. > > Pay attention to be robust where dma_counter wrapping is not a > multiple of period_size or buffer_size. > > This is a revised patch based on feedback from Takashi and Giuliano. > > Signed-off-by: Mark Hills Applied now. Thanks. Takashi