From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757532AbbAIMvz (ORCPT ); Fri, 9 Jan 2015 07:51:55 -0500 Received: from smtp6-g21.free.fr ([212.27.42.6]:28036 "EHLO smtp6-g21.free.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755183AbbAIMvy convert rfc822-to-8bit (ORCPT ); Fri, 9 Jan 2015 07:51:54 -0500 Date: Fri, 9 Jan 2015 13:54:01 +0100 From: Jean-Francois Moine To: Russell King - ARM Linux Cc: Jyri Sarha , Mark Brown , Dave Airlie , Andrew Jackson , alsa-devel@alsa-project.org, devicetree@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v9 1/4] drm/i2c: tda998x: Add DT support for audio Message-ID: <20150109135401.5b270d46@armhf> In-Reply-To: <20150109114529.GH12302@n2100.arm.linux.org.uk> References: <0084acea5a3475a77531d6a77483f36d3469111a.1420628786.git.moinejf@free.fr> <54AE99F5.1010404@ti.com> <20150108174257.557f7ea5@armhf> <54AFA9B0.6040405@ti.com> <20150109123036.4bc4bbf6@armhf> <20150109114529.GH12302@n2100.arm.linux.org.uk> X-Mailer: Claws Mail 3.11.1 (GTK+ 2.24.25; arm-unknown-linux-gnueabihf) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 9 Jan 2015 11:45:29 +0000 Russell King - ARM Linux wrote: > On Fri, Jan 09, 2015 at 12:30:36PM +0100, Jean-Francois Moine wrote: > > In my original version, the audio-ports are a bitmap of the pins, the > > bit 0 being the WS used for I2S. A fully wired tda998x would have been > > as: > > > > audio-ports = <0x03>, <0x04>, <0x09>, <0x11>; > > audio-port-names = "i2s", "spdif", "i2s", "i2s"; > > > > With the new version, it would simply become: > > > > audio-inputs = "i2s", "spdif", "i2s", "i2s"; > > How do you know which i2s inputs to enable? > > Does it make sense for the audio inputs to be mixed like that? > > You will need to enable one i2s for front L+R, and increasingly others > for the additional channels. > > I think we need to understand exactly how the 998x map I2S inputs to the > HDMI channels to avoid making a mistake with the binding; remember, the > binding isn't something that can be easily "bug fixed" at a later date > as anything we come up with now has to be supported long term by the > kernel. The DT describes the hardware configuration. A fully wired tda998x could be a chip with the audio pins connected to: - a kirkwood-like audio device with one I2S and one S/PDIF output, - two other audio devices with one I2S each. The relation between an audio device and the associated pin is done by the definition of the sound card. With S/PDIF, only one stereo channel may be sent, but with I2S, up to 4 stereo channels may be sent. These channels are extracted by the devices connected on the HDMI bus. There is no mixing. An example could be the playing of a multi-language movie: each audio channel carries one language. From the computer view, the playing application sends each language to one sound card. So, this means that the tda998x driver should check that S/PDIF and I2S are not active at the same time, and it should also do a pin OR/AND on I2S start/stop. -- Ken ar c'hentañ | ** Breizh ha Linux atav! ** Jef | http://moinejf.free.fr/