From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jaroslav Kysela Subject: Re: [PATCH v2 00/10] audio timestamping evolutions Date: Fri, 19 Dec 2014 21:38:41 +0100 Message-ID: <54948CD1.4080309@perex.cz> References: <1419009913-3686-1-git-send-email-pierre-louis.bossart@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail1.perex.cz (mail1.perex.cz [77.48.224.245]) by alsa0.perex.cz (Postfix) with ESMTP id 0242B2604F2 for ; Fri, 19 Dec 2014 21:38:43 +0100 (CET) In-Reply-To: <1419009913-3686-1-git-send-email-pierre-louis.bossart@linux.intel.com> 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: Pierre-Louis Bossart , alsa-devel@alsa-project.org List-Id: alsa-devel@alsa-project.org Dne 19.12.2014 v 18:25 Pierre-Louis Bossart napsal(a): > This series of patches was inspired by recent threads on the alsa > mailing list, as well issues detected with existing and upcoming > hardware: I don't like some aspects in the interface: 1) ext_info member is not required - the standard info field has enough free bits 2) the whole struct snd_pcm_status is R/O - _IOR('A', 0x20, struct snd_pcm_status); I believe that it's much better to add new audio_tstamp_type to sw_params, but see (4) 3) accuracy - I would use uint64_t and report accuracy in pico-seconds (range from 0 picoseconds to 18446744 seconds); yes, use next bytes from the reserved part of status struct. the __u32 might be used only for flags 4) if there is a motivation to call / obtain timestamps for multiple purposes (audio tstamp types), then offer to return all these timestamps in one shot rather than do multiple queries (again, use reserved bytes) Thanks, Jaroslav -- Jaroslav Kysela Linux Kernel Sound Maintainer ALSA Project; Red Hat, Inc.