From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pierre-Louis Bossart Subject: Re: [PATCH v2 1/1] alsa-lib: Add snd_pcm_start_at. Date: Tue, 06 Jan 2015 08:42:33 -0600 Message-ID: <54ABF459.8000504@linux.intel.com> References: <1418837267-10896-1-git-send-email-timcussins@eml.cc> <5492A7F9.8090602@eml.cc> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by alsa0.perex.cz (Postfix) with ESMTP id D14FE2610B1 for ; Tue, 6 Jan 2015 15:42:37 +0100 (CET) In-Reply-To: <5492A7F9.8090602@eml.cc> 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: Tim Cussins , Raymond Yau Cc: nstoughton@aether.com, tiwai@suse.de, alsa-devel@alsa-project.org List-Id: alsa-devel@alsa-project.org >> Do your implementation need to set specific start threshold to prevent >> the driver automatically start when you fill the buffer ? > > >> Do the driver allow to start when there is no data ? >> > > It's the responsibility of the client to set the start threshold to a > safe and responsible value. > > It might suit some applications to allow both threshold start _and_ > start_at: My implementation doesn't preclude this. Now I am confused... My understanding was that this feature is similar to SSYNC in HDAudio, where everything is ready, buffers filled, DMAs armed, FIFOs filled and the start condition only opens the last gate at a specific time - possibly with multiple streams starting at the same time. If you add a condition on the start_threshold you really don't need any hardware-driven start, do you? Thanks, -Pierre