Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757155Ab2BHAfl (ORCPT ); Tue, 7 Feb 2012 19:35:41 -0500 Received: from mga03.intel.com ([143.182.124.21]:49081 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756841Ab2BHAfj convert rfc822-to-8bit (ORCPT ); Tue, 7 Feb 2012 19:35:39 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.71,315,1320652800"; d="scan'208";a="64243020" From: "Heasley, Seth" To: David Henningsson CC: Takashi Iwai , "alsa-devel@alsa-project.org" , "perex@perex.cz" , "Ralston, James D" , "linux-kernel@vger.kernel.org" Subject: RE: [alsa-devel] [PATCH 1/6] hda_intel: Add Lynx Point HD Audio Controller DeviceIDs Thread-Topic: [alsa-devel] [PATCH 1/6] hda_intel: Add Lynx Point HD Audio Controller DeviceIDs Thread-Index: AQHM2i6+Xo5tJV2DbkS/GNVTnMZPn5Yby5cAgAACngCAFNe14IAA1AMAgADEgjA= Date: Wed, 8 Feb 2012 00:35:33 +0000 Message-ID: References: <201201231624.31275.seth.heasley@intel.com> <4F1E7DC0.5060208@canonical.com> <4F30ADB6.1000109@canonical.com> In-Reply-To: <4F30ADB6.1000109@canonical.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.22.254.139] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1343 Lines: 29 >> I'm also in favor of not rocking the boat, but I'm curious what >changing this would entail, and what would be the advantage or rationale >for making the change? > >Reading the LPIB register, and reading the DMA position buffer, are two >different methods of reading the current playback (or recording) >position, i e which sample is currently being played back. > >The problem is that some chipsets prefer one method over the other, i e, >only one of the methods work reliably. And if the other method only >breaks occasionally, this can be quite difficult to detect and track >down - we will have users complaining about their audio sometimes either >sounding distorted, maybe not working at all, or just once in a while >glitches. All of these symptoms can have many causes, so deducing that >to a broken playback position is time consuming. That's why I think it's >worth the extra question, to get it right from the start. > >So...thanks in advance for looking it up for us? :-) I'm inquiring about it, but I can say that it seems to work just fine using the DMA position buffer. -Seth -- 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/