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: 6397381 Return-Path: X-Original-To: patchwork-linux-mediatek@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 6141BBEEE1 for ; Wed, 13 May 2015 14:41:14 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 80BDF20397 for ; Wed, 13 May 2015 14:41:13 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id A846D2028D for ; Wed, 13 May 2015 14:41:12 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1YsXqR-0003C5-Hj; Wed, 13 May 2015 14:41:11 +0000 Received: from [210.61.82.184] (helo=mailgw02.mediatek.com) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1YsXpV-0001KP-93; Wed, 13 May 2015 14:40:15 +0000 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: , , , Subject: [RFC PATCH] ALSA: pcm: Modify double acknowledged interrupts check condition 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 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20150513_074013_743900_47A4BA0F X-CRM114-Status: UNSURE ( 7.78 ) X-CRM114-Notice: Please train this message. X-Spam-Score: 1.3 (+) 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 X-BeenThere: linux-mediatek@lists.infradead.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-mediatek" Errors-To: linux-mediatek-bounces+patchwork-linux-mediatek=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, T_RP_MATCHES_RCVD,UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.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;