Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751913AbaAMKs6 (ORCPT ); Mon, 13 Jan 2014 05:48:58 -0500 Received: from mga09.intel.com ([134.134.136.24]:46118 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751770AbaAMKsy (ORCPT ); Mon, 13 Jan 2014 05:48:54 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.95,652,1384329600"; d="scan'208";a="465766323" Message-ID: <1389610131.2326.16.camel@loki> Subject: Re: [alsa-devel] [PATCH] ASoC: dpcm: don't do hw_param when BE has done hw_param From: Liam Girdwood To: Takashi Iwai Cc: "alsa-devel@alsa-project.org" , Mark Brown , "linux-kernel@vger.kernel.org" , Nenghua Cao Date: Mon, 13 Jan 2014 10:48:51 +0000 In-Reply-To: References: <1389332195-15900-1-git-send-email-nhcao@marvell.com> <52CFD7BE.5030907@marvell.com> <1389354435.2293.32.camel@loki> <52CFE0AE.1030606@marvell.com> <1389356948.2293.55.camel@loki> <1389379389.2293.114.camel@loki> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.8.4-0ubuntu1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 2014-01-11 at 10:35 +0100, Takashi Iwai wrote: > At Fri, 10 Jan 2014 18:43:09 +0000, > Liam Girdwood wrote: > > > > On Fri, 2014-01-10 at 14:46 +0100, Takashi Iwai wrote: > > > At Fri, 10 Jan 2014 12:29:08 +0000, > > > Liam Girdwood wrote: > > > > > > > > The intention was to use the existing alsa-lib/tinyalsa PCM hw_params > > APIs. The BE would just export itself to usespace as a PCM (but without > > the capability for direct playback/capture - just format, rate setting) > > Does it mean that, from kernel perspective, a BE creates a dedicated > (virtual) PCM device and expose it to user-space? Or just through > special API? I'm thinking a virtual PCM if you agree. We could keep the same userspace API for configuration OR we could extend the API slightly to add some snd_pcm_virtual_() functions. Extending the API would imply the virtual PCM only supports a subset of PCM API calls (avoiding any confusion/mixing with regular PCM APIs). Thanks Liam -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/