From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lars-Peter Clausen Subject: Re: ASoC: Machine Driver Interaction with Codec Drivers Date: Thu, 9 Jun 2016 12:31:12 +0200 Message-ID: <57594570.7020100@metafoo.de> References: <0BE0E679-A120-4330-8291-315750457145@xenotropic.com> <57586E79.4010309@metafoo.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from www381.your-server.de (www381.your-server.de [78.46.137.84]) by alsa0.perex.cz (Postfix) with ESMTP id 606232608B3 for ; Thu, 9 Jun 2016 12:31:15 +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: Jeremy McDermond , alsa-devel@alsa-project.org List-Id: alsa-devel@alsa-project.org On 06/09/2016 11:49 AM, Takashi Iwai wrote: > On Wed, 08 Jun 2016 21:14:01 +0200, > Lars-Peter Clausen wrote: >> >> Hi, >> >> No this is currently not really supported. There were some ideas for this a >> long long time ago, but it never got implemented. And today basically >> everybody takes care of hiding the controls from userspace. >> >> That does not mean it does not make sense to have such a feature, but it >> needs somebody with a motivation to implement it. > > The devils live in details. Actually a primary question is in which > level we should cover it. For example, can we disable DAPM pins from > the machine driver? This will reduce not only kctls but DAPM paths. > Or should we mark kctls just as invisible? Or, would it be suitable > rather to hide such a thing in user-space? For DAPM we already do this. Even automatically the DAPM core is capable of figuring out which paths are unused and will never be powered-up. The path will still exist in the graph but it will be ignored for all operations and not significantly affect performance. And I think the idea back then was to track which controls are on which paths and if it is on a non-connected path disable the control. What's a bit tricky is if you have a mixer or mux and only some of the output/input paths are not connected. Also for most controls we do not have the information where they are placed within the graph.