Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753016AbaJ1PFW (ORCPT ); Tue, 28 Oct 2014 11:05:22 -0400 Received: from mailapp01.imgtec.com ([195.59.15.196]:11744 "EHLO mailapp01.imgtec.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750900AbaJ1PFU (ORCPT ); Tue, 28 Oct 2014 11:05:20 -0400 Message-ID: <544FB0AC.4020205@imgtec.com> Date: Tue, 28 Oct 2014 15:05:16 +0000 From: Qais Yousef User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.8.0 MIME-Version: 1.0 To: Greg Kroah-Hartman CC: Clemens Ladisch , , "Arnd Bergmann" , , , Neil Jones Subject: Re: [PATCH 00/11] Add AXD Audio Processing IP driver References: <1414495589-8579-1-git-send-email-qais.yousef@imgtec.com> <544F8439.4080402@ladisch.de> <544F97A4.7080209@imgtec.com> <20141028141348.GD18384@kroah.com> In-Reply-To: <20141028141348.GD18384@kroah.com> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [192.168.154.94] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/28/2014 02:13 PM, Greg Kroah-Hartman wrote: > On Tue, Oct 28, 2014 at 01:18:28PM +0000, Qais Yousef wrote: >> On 10/28/2014 11:55 AM, Clemens Ladisch wrote: >>> Qais Yousef wrote: >>>> AXD Audio Processing IP performs audio decoding, encoding, mixing, equalisation, >>>> synchronisation and playback. >>> What exactly do you mean with "synchronisation" and "playback"? >> Synchronisation refers to accurate audio playout relative to a master >> clock source including compensation of drift between the master clock >> source and the playout clock of the audio hardware. Hence allowing >> synchronised audio playout across multiple independent devices. >> >> Playback simple refers to the fact that AXD is capable of managing audio >> playout hardware like I2S and SPDIF interfaces. >> >> >>>> It doesn't fit in alsa subsystem but I Cced them to confirm. >>> ... because those two words sound like something that a sound card could do. >> The problem mainly stems from the fact that we take a variety of >> compressed audio as input and we could perform audio encoding. The >> problem with the compressed audio is that the range of decoders and >> configuration supported in alsa is limited and there's no support for >> taking raw pcm and producing compressed output. I'm not an expert on >> alsa but when I looked it looked like there's more infra structure >> required. >> >> The following not supported points from Documentation/sound/alsa/compress_offload.txt affect us: >> >> - Volume control/routing is not handled by this API. Devices exposing a >> compressed data interface will be considered as regular ALSA devices; >> volume changes and routing information will be provided with regular >> ALSA kcontrols. >> >> - Embedded audio effects. Such effects should be enabled in the same >> manner, no matter if the input was PCM or compressed. >> >> - Encoding/decoding acceleration is not supported as mentioned >> above. It is possible to route the output of a decoder to a capture >> stream, or even implement transcoding capabilities. This routing >> would be enabled with ALSA kcontrols. > So instead you created a one-off api just for this hardware? Ick, no, > please work with the audio developers to incorporate it into the > standard Linux audio apis so that everyone can benifit and not require > special userspace programs to drive this hardware. > > thanks, > > greg k-h OK. I'll wait to hear from alsa developers to see the extent of work required. I can't see it being trivial though. Would it be possible for this to be accepted into staging until this is resolved? Thanks, Qais -- 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/