From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stefan Richter Subject: Re: Echo Fireworks control protocol (was Re: Sample program for hwdep interface) Date: Sun, 9 Feb 2014 15:51:45 +0100 Message-ID: <20140209155145.2175d147@stein> References: <1387545269-3875-1-git-send-email-o-takashi@sakamocchi.jp> <52B45837.2080804@sakamocchi.jp> <20131221101123.GA17855@marvin.atrad.com.au> <52C93F8B.1010701@sakamocchi.jp> <20140112142230.4aacdc9e@stein> <52D2B41B.7090505@sakamocchi.jp> <20140202145850.1f8684b3@stein> <52F62FA0.6040809@sakamocchi.jp> <20140209114228.GB15049@marvin.atrad.com.au> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20140209114228.GB15049@marvin.atrad.com.au> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux1394-devel-bounces@lists.sourceforge.net To: Jonathan Woithe Cc: alsa-devel@alsa-project.org, linux1394-devel@lists.sourceforge.net, ffado-devel@lists.sf.net List-Id: alsa-devel@alsa-project.org On Feb 09 Jonathan Woithe wrote: > On Sat, Feb 08, 2014 at 10:22:40PM +0900, Takashi Sakamoto wrote: > > >I understood from Clemens' comments that ... the mixer applications are > > >supposed to use firewire-cdev for all their other dealings with the audio > > >devices. (Clemens and Jonathan, correct me if I misunderstood or if I > > >forgot other control and status I/O that is only possible with direct > > >cooperation by the ALSA driver.) > > > > I don't know his future plan. But according to his advices, my > > current work is to focus on streaming driver. Currently the > > functionality to control device's internal mixer should be > > implemented in user-land application, not in ALSA drivers. > > As per an earlier followup, the current intention is indeed to keep the > mixer control in userspace. Sure, definitely; my point was that the kernel ABI which userspace mixer applications are going to use could be a) the ALSA hwdep interface, or b) the ALSA hwdep interface together with firewire-core's firewire-cdev interface, but I understood that b) is the first choice. Specifically, provide in ALSA hwdep only the absolutely necessary interfaces and do as much as possible via firewire-cdev. In contrast, it can't be firewire-cdev alone because of streaming on/off state influences what can be controlled, and because some devices embed status into the isochronous stream (MotU? RME?), and because some devices (which ones?) may have write-only registers, of which both streaming driver and mixer application want to know what is being written there. Furthermore, it can't be a kernel interface like sysfs or configfs because of the complexity and variety of control protocols of FireWire audio devices. -- Stefan Richter -=====-====- --=- -=--= http://arcgraph.de/sr/ ------------------------------------------------------------------------------ Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121051231&iu=/4140/ostg.clktrk