Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756594Ab2FTLDY (ORCPT ); Wed, 20 Jun 2012 07:03:24 -0400 Received: from mga14.intel.com ([143.182.124.37]:29955 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754037Ab2FTLDX (ORCPT ); Wed, 20 Jun 2012 07:03:23 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.71,315,1320652800"; d="scan'208";a="158599289" Subject: Re: [PATCH v2 3/3] ASoC: dmaengine-pcm: Add support for querying stream position from DMA driver From: Vinod Koul To: Lars-Peter Clausen Cc: Mark Brown , Liam Girdwood , Russell King , Ola Lilja , Shawn Guo , Mika Westerberg , alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org In-Reply-To: <1339438302-12417-3-git-send-email-lars@metafoo.de> References: <1339438302-12417-1-git-send-email-lars@metafoo.de> <1339438302-12417-3-git-send-email-lars@metafoo.de> Content-Type: text/plain; charset="UTF-8" Date: Wed, 20 Jun 2012 16:25:33 +0530 Message-ID: <1340189733.1927.1651.camel@vkoul-udesk3> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1215 Lines: 24 On Mon, 2012-06-11 at 20:11 +0200, Lars-Peter Clausen wrote: > Currently the sound dmaengine pcm helper functions implement the pcm_pointer > callback by trying to count the number of elapsed periods. This is done by > advancing the stream position in the dmaengine callback by one period. > Unfortunately there is no guarantee that the callback will be called for each > elapsed period. It may be possible that under high system load it is only called > once for multiple elapsed periods. This patch addresses the issue by > implementing support for querying the current stream position directly from the > dmaengine driver. Since not all dmaengine drivers support reporting the stream > position yet the old period counting implementation is kept for now. > > Furthermore the new mechanism allows to report the stream position with a > sub-period granularity, given that the dmaengine driver supports this. > Acked-by: Vinod Koul -- ~Vinod -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/