From patchwork Wed May 13 14:39:03 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Koro Chen X-Patchwork-Id: 6397361 Return-Path: X-Original-To: patchwork-alsa-devel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 10D90BEEE1 for ; Wed, 13 May 2015 14:40:08 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 45FB22042A for ; Wed, 13 May 2015 14:40:07 +0000 (UTC) Received: from alsa0.perex.cz (alsa0.perex.cz [77.48.224.243]) by mail.kernel.org (Postfix) with ESMTP id 2C76C2028D for ; Wed, 13 May 2015 14:40:03 +0000 (UTC) Received: by alsa0.perex.cz (Postfix, from userid 1000) id ADDF4265D80; Wed, 13 May 2015 16:40:01 +0200 (CEST) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 Received: from alsa0.perex.cz (localhost [IPv6:::1]) by alsa0.perex.cz (Postfix) with ESMTP id 1752E265D05; Wed, 13 May 2015 16:39:54 +0200 (CEST) X-Original-To: alsa-devel@alsa-project.org Delivered-To: alsa-devel@alsa-project.org Received: by alsa0.perex.cz (Postfix, from userid 1000) id AECE8265D05; Wed, 13 May 2015 16:39:52 +0200 (CEST) Received: from mailgw02.mediatek.com (unknown [210.61.82.184]) by alsa0.perex.cz (Postfix) with ESMTP id 3010F265CBE for ; Wed, 13 May 2015 16:39:45 +0200 (CEST) X-Listener-Flag: 11101 Received: from mtkhts07.mediatek.inc [(172.21.101.69)] by mailgw02.mediatek.com (envelope-from ) (mhqrelay.mediatek.com ESMTP with TLS) with ESMTP id 235602901; Wed, 13 May 2015 22:39:37 +0800 Received: from mtkslt301 (10.21.14.114) by mtkhts07.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 14.3.181.6; Wed, 13 May 2015 22:39:36 +0800 Received: by mtkslt301 (Postfix, from userid 11333) id 0787318384F; Wed, 13 May 2015 22:39:35 +0800 (CST) From: Koro Chen To: , , , Date: Wed, 13 May 2015 22:39:03 +0800 Message-ID: <1431527943-64178-1-git-send-email-koro.chen@mediatek.com> X-Mailer: git-send-email 1.8.1.1.dirty MIME-Version: 1.0 X-MTK: N Cc: alsa-devel@alsa-project.org, srv_heupstream@mediatek.com, s.hauer@pengutronix.de, linux-kernel@vger.kernel.org, Koro Chen , linux-mediatek@lists.infradead.org, linux-arm-kernel@lists.infradead.org Subject: [alsa-devel] [RFC PATCH] ALSA: pcm: Modify double acknowledged interrupts check condition X-BeenThere: alsa-devel@alsa-project.org X-Mailman-Version: 2.1.14 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-bounces@alsa-project.org X-Virus-Scanned: ClamAV using ClamSMTP Currently in snd_pcm_update_hw_ptr0 during interrupt, we consider there were double acknowledged interrupts when: 1. HW reported pointer is smaller than expected, and 2. Time from last update time (hdelta) is over half a buffer time. However, when HW reported pointer is only a few bytes smaller than expected, and when hdelta is just a little larger than half a buffer time (e.g. ping-pong buffer), it wrongly treats this IRQ as double acknowledged. The condition #2 uses jiffies, but jiffies is not high resolution since it is integer. We should consider jiffies inaccuracy. Signed-off-by: Koro Chen --- sound/core/pcm_lib.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c index ac6b33f..7d45645 100644 --- a/sound/core/pcm_lib.c +++ b/sound/core/pcm_lib.c @@ -339,7 +339,7 @@ static int snd_pcm_update_hw_ptr0(struct snd_pcm_substream *substream, if (delta > new_hw_ptr) { /* check for double acknowledged interrupts */ hdelta = curr_jiffies - runtime->hw_ptr_jiffies; - if (hdelta > runtime->hw_ptr_buffer_jiffies/2) { + if (hdelta > runtime->hw_ptr_buffer_jiffies/2 + 1) { hw_base += runtime->buffer_size; if (hw_base >= runtime->boundary) { hw_base = 0;