From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Brown Subject: Re: [RFC/PATCH v6 03/12] media: Entities, pads and links Date: Thu, 25 Nov 2010 13:41:35 +0000 Message-ID: <20101125134135.GB24208@opensource.wolfsonmicro.com> References: <1290652099-15102-1-git-send-email-laurent.pinchart@ideasonboard.com> <1290652099-15102-4-git-send-email-laurent.pinchart@ideasonboard.com> <4CEE2E7D.6060608@ladisch.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <4CEE2E7D.6060608@ladisch.de> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: alsa-devel-bounces@alsa-project.org Errors-To: alsa-devel-bounces@alsa-project.org To: Clemens Ladisch Cc: alsa-devel@alsa-project.org, sakari.ailus@maxwell.research.nokia.com, linux-kernel@vger.kernel.org, Laurent Pinchart , lennart@poettering.net, linux-omap@vger.kernel.org, linux-media@vger.kernel.org List-Id: linux-omap@vger.kernel.org On Thu, Nov 25, 2010 at 10:38:05AM +0100, Clemens Ladisch wrote: > In USB and HD audio devices, all links are immutable, and the routing > is controlled by 'selector' entities that activate exactly one of their > input pads. In userspace, this entity shows up as a mixer control. > I guess it would be possible to map the ACTIVE flag onto these controls. Ditto for ASoC, mostly. > Alternatively, entities can have 'mute' mixer controls associated with > their pads. In this case, multiple unmuted inputs would be mixed > together. > ALSA has PCM and MIDI devices, and several types of mixer controls. > (It also has hardware dependent and timer devices, but I don't think > these would need topology information.) So we need at least these: > MEDIA_ENTITY_TYPE_NODE_ALSA_PCM > MEDIA_ENTITY_TYPE_NODE_ALSA_MIDI > MEDIA_ENTITY_TYPE_SUBDEV_ALSA_CONTROL > Furthermore, topology information is also needed for entities not > associated with a mixer control, such as microphones, speakers, jacks/ > connectors, and effect units. These entities are defined in the USB and > HD audio specifications, but are not yet handled by ALSA. All this and more in the embedded case - digital audio link nodes and DSP I/O nodes (could possibly do those as digital audio ones) spring to mind. Also bear in mind that embedded devices can get *very* large - a mobile phone audio system can have of the order of 100 nodes in the graph. > ALSA devices are not addressed by their device node but with card/device/ > subdevice numbers; mixer controls have numeric IDs, unique per card: > > struct { > int card; > int device; > int subdevice; > } alsa_device; > struct { > int card; > int numid; > } alsa_control; For the embedded stuff we also have a bunch of stuff in the graph which may not be visible to userspace at all at present and would just have a string based identifier.