From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from alsa0.perex.cz (alsa0.perex.cz [77.48.224.243]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 14D66C4345F for ; Tue, 30 Apr 2024 16:29:12 +0000 (UTC) Received: from alsa1.perex.cz (alsa1.perex.cz [207.180.221.201]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by alsa0.perex.cz (Postfix) with ESMTPS id 6A432B6A; Tue, 30 Apr 2024 18:29:00 +0200 (CEST) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa0.perex.cz 6A432B6A DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=alsa-project.org; s=default; t=1714494550; bh=u27bGd4V0G96pi8D9gvQaaGAkmUp7bSeoFGhoO/A8XE=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-Id: List-Archive:List-Help:List-Owner:List-Post:List-Subscribe: List-Unsubscribe:From; b=i/K+Iz6kEpOQfau3hc+tOMiI1a2+/DRwWk36X0IHlNwnrTjtjCPqo7BZw6XW0SUIU PGjGYawJCTNakiaTGm9Oa8SNamQPlcD+YyQUbElE4qNXclv0cEXi9WPz/CDzlUt9cs pgIScvGBq9oa90gUvQPfugvwq3NlWajBSgXgdDDM= Received: by alsa1.perex.cz (Postfix, from userid 50401) id A2D53F80266; Tue, 30 Apr 2024 18:28:28 +0200 (CEST) Received: from mailman-core.alsa-project.org (mailman-core.alsa-project.org [10.254.200.10]) by alsa1.perex.cz (Postfix) with ESMTP id 57FE3F8059F; Tue, 30 Apr 2024 18:28:28 +0200 (CEST) Received: by alsa1.perex.cz (Postfix, from userid 50401) id 00DD7F80266; Tue, 30 Apr 2024 18:28:22 +0200 (CEST) Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by alsa1.perex.cz (Postfix) with ESMTPS id 6A13FF8003C for ; Tue, 30 Apr 2024 18:28:05 +0200 (CEST) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa1.perex.cz 6A13FF8003C Authentication-Results: alsa1.perex.cz; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=OCiswKJN Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id 188D8614AE; Tue, 30 Apr 2024 16:28:00 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8B2C0C2BBFC; Tue, 30 Apr 2024 16:27:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1714494479; bh=u27bGd4V0G96pi8D9gvQaaGAkmUp7bSeoFGhoO/A8XE=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=OCiswKJNOu0sfl6Oov4FuPcbIbdEIAUmabyt1qX3yut7X6jtOUtNez6dT2UiSY6rd UmyD5qSfJyubO8kEyMTErYCZFFaSEvieHPnBf/O2A4ovxK9v590e5J/L2+RHeaDufu 3aLtZ/r7wpN+MjcKfycQd3ZruzmmING/5cJxi/GHSRw/rwljtTiMnDsS3wfXBynfUg B4fyEoVTtsQN7u/8lKgsS41p9O3Kp948p3GmD1zd0hA8sXXiyo/YefgCGzFrpWqMJ/ rBedlv16kTuD1X+QNkL5ru7Fpfk26uvfe2RSEm1+a4lgLtmlZkk9sQ1OLC8jaC+EHZ oFr1SVAafVguA== Date: Tue, 30 Apr 2024 17:27:52 +0100 From: Mauro Carvalho Chehab To: Mark Brown Cc: Sebastian Fricke , Shengjiu Wang , hverkuil@xs4all.nl, sakari.ailus@iki.fi, tfiga@chromium.org, m.szyprowski@samsung.com, linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, shengjiu.wang@gmail.com, Xiubo.Lee@gmail.com, festevam@gmail.com, nicoleotsuka@gmail.com, lgirdwood@gmail.com, perex@perex.cz, tiwai@suse.com, alsa-devel@alsa-project.org, linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH v15 00/16] Add audio support in v4l2 framework Message-ID: <20240430172752.20ffcd56@sal.lan> In-Reply-To: References: <1710834674-3285-1-git-send-email-shengjiu.wang@nxp.com> <20240430082112.jrovosb6lgblgpfg@basti-XPS-13-9310> X-Mailer: Claws Mail 4.2.0 (GTK 3.24.41; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Message-ID-Hash: PAMC3CB3XXQPUXHQTHBHNDCQ2QULT76Z X-Message-ID-Hash: PAMC3CB3XXQPUXHQTHBHNDCQ2QULT76Z X-MailFrom: mchehab@kernel.org X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; header-match-alsa-devel.alsa-project.org-0; header-match-alsa-devel.alsa-project.org-1; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header X-Mailman-Version: 3.3.9 Precedence: list List-Id: "Alsa-devel mailing list for ALSA developers - http://www.alsa-project.org" Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: Em Tue, 30 Apr 2024 23:46:03 +0900 Mark Brown escreveu: > On Tue, Apr 30, 2024 at 10:21:12AM +0200, Sebastian Fricke wrote: > > > first of all thanks for all of this work and I am very sorry for only > > emerging this late into the series, I sadly didn't notice it earlier. > > It might be worth checking out the discussion on earlier versions... > > > 1. The biggest objection is, that the Linux Kernel has a subsystem > > specifically targeted for audio devices, adding support for these > > devices in another subsystem are counterproductive as they work around > > the shortcomings of the audio subsystem while forcing support for a > > device into a subsystem that was never designed for such devices. > > Instead, the audio subsystem has to be adjusted to be able to support > > all of the required workflows, otherwise, the next audio driver with > > similar requirements will have to move to the media subsystem as well, > > the audio subsystem would then never experience the required change and > > soon we would have two audio subsystems. > > The discussion around this originally was that all the audio APIs are > very much centered around real time operations rather than completely > async memory to memory operations and that it's not clear that it's > worth reinventing the wheel simply for the sake of having things in > ALSA when that's already pretty idiomatic for the media subsystem. It > wasn't the memory to memory bit per se, it was the disconnection from > any timing. The media subsystem is also centered around real time. Without real time, you can't have a decent video conference system. Having mem2mem transfers actually help reducing real time delays, as it avoids extra latency due to CPU congestion and/or data transfers from/to userspace. > > > So instead of hammering a driver into the wrong destination, I would > > suggest bundling our forces and implementing a general memory-to-memory > > framework that both the media and the audio subsystem can use, that > > addresses the current shortcomings of the implementation and allows you > > to upload the driver where it is supposed to be. > > That doesn't sound like an immediate solution to maintainer overload > issues... if something like this is going to happen the DRM solution > does seem more general but I'm not sure the amount of stop energy is > proportionate. I don't think maintainer overload is the issue here. The main point is to avoid a fork at the audio uAPI, plus the burden of re-inventing the wheel with new codes for audio formats, new documentation for them, etc. Regards, Mauro From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D90D9C4345F for ; Tue, 30 Apr 2024 16:28:45 +0000 (UTC) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=OCiswKJN; dkim-atps=neutral Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4VTQcX3YNhz3cVK for ; Wed, 1 May 2024 02:28:44 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=OCiswKJN; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=kernel.org (client-ip=2604:1380:4641:c500::1; helo=dfw.source.kernel.org; envelope-from=mchehab@kernel.org; receiver=lists.ozlabs.org) Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4VTQbl3Qnmz3cPW for ; Wed, 1 May 2024 02:28:03 +1000 (AEST) Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id 188D8614AE; Tue, 30 Apr 2024 16:28:00 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8B2C0C2BBFC; Tue, 30 Apr 2024 16:27:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1714494479; bh=u27bGd4V0G96pi8D9gvQaaGAkmUp7bSeoFGhoO/A8XE=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=OCiswKJNOu0sfl6Oov4FuPcbIbdEIAUmabyt1qX3yut7X6jtOUtNez6dT2UiSY6rd UmyD5qSfJyubO8kEyMTErYCZFFaSEvieHPnBf/O2A4ovxK9v590e5J/L2+RHeaDufu 3aLtZ/r7wpN+MjcKfycQd3ZruzmmING/5cJxi/GHSRw/rwljtTiMnDsS3wfXBynfUg B4fyEoVTtsQN7u/8lKgsS41p9O3Kp948p3GmD1zd0hA8sXXiyo/YefgCGzFrpWqMJ/ rBedlv16kTuD1X+QNkL5ru7Fpfk26uvfe2RSEm1+a4lgLtmlZkk9sQ1OLC8jaC+EHZ oFr1SVAafVguA== Date: Tue, 30 Apr 2024 17:27:52 +0100 From: Mauro Carvalho Chehab To: Mark Brown Subject: Re: [PATCH v15 00/16] Add audio support in v4l2 framework Message-ID: <20240430172752.20ffcd56@sal.lan> In-Reply-To: References: <1710834674-3285-1-git-send-email-shengjiu.wang@nxp.com> <20240430082112.jrovosb6lgblgpfg@basti-XPS-13-9310> X-Mailer: Claws Mail 4.2.0 (GTK 3.24.41; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: nicoleotsuka@gmail.com, alsa-devel@alsa-project.org, lgirdwood@gmail.com, Sebastian Fricke , Xiubo.Lee@gmail.com, festevam@gmail.com, Shengjiu Wang , tiwai@suse.com, linux-kernel@vger.kernel.org, tfiga@chromium.org, hverkuil@xs4all.nl, linuxppc-dev@lists.ozlabs.org, sakari.ailus@iki.fi, perex@perex.cz, linux-media@vger.kernel.org, shengjiu.wang@gmail.com, m.szyprowski@samsung.com Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Em Tue, 30 Apr 2024 23:46:03 +0900 Mark Brown escreveu: > On Tue, Apr 30, 2024 at 10:21:12AM +0200, Sebastian Fricke wrote: > > > first of all thanks for all of this work and I am very sorry for only > > emerging this late into the series, I sadly didn't notice it earlier. > > It might be worth checking out the discussion on earlier versions... > > > 1. The biggest objection is, that the Linux Kernel has a subsystem > > specifically targeted for audio devices, adding support for these > > devices in another subsystem are counterproductive as they work around > > the shortcomings of the audio subsystem while forcing support for a > > device into a subsystem that was never designed for such devices. > > Instead, the audio subsystem has to be adjusted to be able to support > > all of the required workflows, otherwise, the next audio driver with > > similar requirements will have to move to the media subsystem as well, > > the audio subsystem would then never experience the required change and > > soon we would have two audio subsystems. > > The discussion around this originally was that all the audio APIs are > very much centered around real time operations rather than completely > async memory to memory operations and that it's not clear that it's > worth reinventing the wheel simply for the sake of having things in > ALSA when that's already pretty idiomatic for the media subsystem. It > wasn't the memory to memory bit per se, it was the disconnection from > any timing. The media subsystem is also centered around real time. Without real time, you can't have a decent video conference system. Having mem2mem transfers actually help reducing real time delays, as it avoids extra latency due to CPU congestion and/or data transfers from/to userspace. > > > So instead of hammering a driver into the wrong destination, I would > > suggest bundling our forces and implementing a general memory-to-memory > > framework that both the media and the audio subsystem can use, that > > addresses the current shortcomings of the implementation and allows you > > to upload the driver where it is supposed to be. > > That doesn't sound like an immediate solution to maintainer overload > issues... if something like this is going to happen the DRM solution > does seem more general but I'm not sure the amount of stop energy is > proportionate. I don't think maintainer overload is the issue here. The main point is to avoid a fork at the audio uAPI, plus the burden of re-inventing the wheel with new codes for audio formats, new documentation for them, etc. Regards, Mauro