From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wu Fengguang Subject: multi-channel playback regression Date: Thu, 23 Jul 2009 14:53:45 +0800 Message-ID: <20090723065345.GA1884@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mga14.intel.com (mga14.intel.com [143.182.124.37]) by alsa0.perex.cz (Postfix) with ESMTP id 0905710380B for ; Thu, 23 Jul 2009 08:53:49 +0200 (CEST) Content-Disposition: inline List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: alsa-devel-bounces@alsa-project.org Errors-To: alsa-devel-bounces@alsa-project.org To: Takashi Iwai Cc: alsa-devel@alsa-project.org List-Id: alsa-devel@alsa-project.org Hi Takashi, When doing multi-channel playback tests on IbexPeak, I found that the following patch makes the playback enter an infinite loop, repeatedly playing a range of ~0.5s audio content. (Seems that some buffer pointer can never advance.) Thanks, Fengguang --- 79452f0a28aa5a40522c487b42a5fc423647ad98 Author: Takashi Iwai Date: Wed Jul 22 12:51:51 2009 +0200 ALSA: pcm - Fix regressions with VMware VMware tends to report PCM positions and period updates at utterly wrong timing. This screws up the recent PCM core code that tries to correct the position based on the irq timing. Now, when a backward irq position is detected, skip the update instead of rebasing. (This is almost the old behavior before 2.6.30.) Signed-off-by: Takashi Iwai diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c index 333e4dd..3b673e2 100644 --- a/sound/core/pcm_lib.c +++ b/sound/core/pcm_lib.c @@ -244,18 +244,27 @@ static int snd_pcm_update_hw_ptr_interrupt(struct snd_pcm_substream *substream) delta = new_hw_ptr - hw_ptr_interrupt; } if (delta < 0) { - delta += runtime->buffer_size; + if (runtime->periods == 1) + delta += runtime->buffer_size; if (delta < 0) { hw_ptr_error(substream, "Unexpected hw_pointer value " "(stream=%i, pos=%ld, intr_ptr=%ld)\n", substream->stream, (long)pos, (long)hw_ptr_interrupt); +#if 1 + /* simply skipping the hwptr update seems more + * robust in some cases, e.g. on VMware with + * inaccurate timer source + */ + return 0; /* skip this update */ +#else /* rebase to interrupt position */ hw_base = new_hw_ptr = hw_ptr_interrupt; /* align hw_base to buffer_size */ hw_base -= hw_base % runtime->buffer_size;