From mboxrd@z Thu Jan 1 00:00:00 1970 From: Clemens Ladisch Subject: Re: [RFC PATCH 1/11] expose sound device topology information Date: Tue, 04 Sep 2012 20:02:57 +0200 Message-ID: <50464251.7030601@ladisch.de> References: <503BF48E.1090100@ladisch.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from out1-smtp.messagingengine.com (out1-smtp.messagingengine.com [66.111.4.25]) by alsa0.perex.cz (Postfix) with ESMTP id 6329B265285 for ; Tue, 4 Sep 2012 20:03:59 +0200 (CEST) In-Reply-To: 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: Takashi Iwai Cc: alsa-devel@alsa-project.org, Mark Brown List-Id: alsa-devel@alsa-project.org Takashi Iwai wrote: > Clemens Ladisch wrote: >> The media controller API allows prividing routing >> information, but its implementation does not quite fit the sound >> drivers: >> * it allows reconfiguration of links, but not in a way that would be >> useful for ALSA selector controls I didn't mention why: it is not possible to enable two links to a sink pad, and neither can one change the state of two links atomically; therefore, an enum control with exactly one active input cannot be modelled. (It might be possible to change the media controller API to allow this.) Mute controls _could_ be modelled by disabling links, but with all other mixer control types not represented in the media controller API, this doesn't appear to be very useful. > But what about multiple codecs on a single control device? Can they > be represented well? The driver has to choose the entity IDs so that they don't conflict; something like busnumber<<20 | codecaddress<<10 | nodeid. The USB audio driver will have this problem if there are multiple audio control interfaces, so I guess it will have to include the interface number. Regards, Clemens