From mboxrd@z Thu Jan 1 00:00:00 1970 From: Clemens Ladisch Subject: Re: [RFC] ALSA: Reduce delay for a blocking pcm_drain. Date: Mon, 30 Sep 2013 16:13:38 +0200 Message-ID: <52498712.5080002@ladisch.de> References: <1380340785-30427-1-git-send-email-dgreid@chromium.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from out1-smtp.messagingengine.com (out1-smtp.messagingengine.com [66.111.4.25]) by alsa0.perex.cz (Postfix) with ESMTP id 2E646261A50 for ; Mon, 30 Sep 2013 16:13:41 +0200 (CEST) In-Reply-To: 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 To: Raymond Yau , Dylan Reid Cc: tiwai@suse.de, alsa-devel@alsa-project.org List-Id: alsa-devel@alsa-project.org Raymond Yau wrote: >> To test this I opened a pcm and set no period wakeups, played a few samples and >> then called drain, which hung indefinitely. Using a USB headset with a >> max period size of 128k but only 15ms of the buffer filled, having the >> drain time shorter without losing samples makes a blocking call >> feasible. > > Do you mean that you tested on a patched version of USB audio driver since > only three drivers support SNDRV_PCM_INFO_NO_PERIOD_WAKEUP The flag is ignored if not supported. In this test, the important part was the large period size. Regards, Clemens