From mboxrd@z Thu Jan 1 00:00:00 1970 From: Clemens Ladisch Subject: Re: snd-fireworks requires larger period sizes than FFADO Date: Mon, 23 Nov 2015 11:40:56 +0100 Message-ID: <5652ED38.6080409@ladisch.de> References: <56510A5F.4080004@gmx.de> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: quoted-printable Return-path: Received: from dehamd003.servertools24.de (dehamd003.servertools24.de [31.47.254.18]) by alsa0.perex.cz (Postfix) with ESMTP id 74DCC265205 for ; Mon, 23 Nov 2015 11:40:57 +0100 (CET) In-Reply-To: <56510A5F.4080004@gmx.de> 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: =?UTF-8?Q?Dominic_Sacr=c3=a9?= , alsa-devel@alsa-project.org List-Id: alsa-devel@alsa-project.org Dominic Sacr=E9 wrote: > I'm trying to use an Echo AudioFire 4 with the snd-fireworks driver. > With FFADO the device works reasonably well at a period size of > 64 samples (on a PREEMPT_RT kernel), whereas with snd-fireworks the > lowest possible period size seems to be 256 samples. > > The lowest achievable analog roundtrip latency seems to be around 19ms > (at 2x256 frames), as opposed to 8.3ms with FFADO (at 2x64). Are there > any known limitations of the snd-fireworks driver in this regard? At the moment, the driver uses a minimum period size of 5 ms. You could try reducing INTERRUPT_INTERVAL and the parameter to snd_pcm_hw_constraint_minmax() in sound/firewire/amdtp-stream.c, and recompiling the driver. Regards, Clemens