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 X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E073AC433DB for ; Wed, 24 Feb 2021 08:53:26 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 1E3CF64EBB for ; Wed, 24 Feb 2021 08:53:24 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1E3CF64EBB Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=alsa-devel-bounces@alsa-project.org Received: from alsa1.perex.cz (alsa1.perex.cz [207.180.221.201]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by alsa0.perex.cz (Postfix) with ESMTPS id A0E9B1675; Wed, 24 Feb 2021 09:52:32 +0100 (CET) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa0.perex.cz A0E9B1675 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=alsa-project.org; s=default; t=1614156802; bh=dxPqNfWsjzx0Tk1dRTMC7zxTcnoePr/tJw+aEk7sJ0I=; h=Date:From:To:Subject:In-Reply-To:References:Cc:List-Id: List-Unsubscribe:List-Archive:List-Post:List-Help:List-Subscribe: From; b=M3SIfKvO88rHv/+v2IUa9N1+cjS0XCH0ly7UalXdLKLKnPMnuJdKsugkOSwjsIkV3 fph5oCNnrpJ1Byf3p5YngjkTg/HL5BRWxhHWMy3wsGm6LDIN16T3ORxfMjvWi9kOb9 fbcr3o0vjXJ6siZ1XbAQzTbgfzJJog6VFYbIrYiw= Received: from alsa1.perex.cz (localhost.localdomain [127.0.0.1]) by alsa1.perex.cz (Postfix) with ESMTP id 3B685F80161; Wed, 24 Feb 2021 09:52:32 +0100 (CET) Received: by alsa1.perex.cz (Postfix, from userid 50401) id 698C7F8016C; Wed, 24 Feb 2021 09:52:29 +0100 (CET) Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by alsa1.perex.cz (Postfix) with ESMTPS id C8DFFF80129 for ; Wed, 24 Feb 2021 09:52:21 +0100 (CET) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa1.perex.cz C8DFFF80129 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 18504AF55; Wed, 24 Feb 2021 08:52:21 +0000 (UTC) Date: Wed, 24 Feb 2021 09:52:20 +0100 Message-ID: From: Takashi Iwai To: Jaroslav Kysela Subject: Re: [RFC 2/2] ASoC: rt5670: Add LED trigger support In-Reply-To: <776b4ad9-2612-b08a-cb76-c3e1ce02388a@perex.cz> References: <20210215142419.308651-1-hdegoede@redhat.com> <20210215142419.308651-3-hdegoede@redhat.com> <20210223134506.GF5116@sirena.org.uk> <578b1ee3-f426-c5b5-bc78-5a91108ebdc8@redhat.com> <20210223140930.GH5116@sirena.org.uk> <5c6a21c1-7107-3351-25be-c007b0b946d3@perex.cz> <776b4ad9-2612-b08a-cb76-c3e1ce02388a@perex.cz> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI/1.14.6 (Maruoka) FLIM/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL/10.8 Emacs/25.3 (x86_64-suse-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=US-ASCII Cc: Oder Chiou , alsa-devel@alsa-project.org, Liam Girdwood , Hans de Goede , Mark Brown , Bard Liao X-BeenThere: alsa-devel@alsa-project.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: "Alsa-devel mailing list for ALSA developers - http://www.alsa-project.org" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: alsa-devel-bounces@alsa-project.org Sender: "Alsa-devel" On Wed, 24 Feb 2021 09:14:41 +0100, Jaroslav Kysela wrote: > > Dne 24. 02. 21 v 8:12 Takashi Iwai napsal(a): > > On Tue, 23 Feb 2021 21:56:16 +0100, > > Jaroslav Kysela wrote: > >> > >> Dne 23. 02. 21 v 17:20 Takashi Iwai napsal(a): > >>>>> Of course, this implementation would make the integration much easier, > >>>>> and that's a big benefit. So I have a mixed feeling and not decided > >>>>> yet whether we should go for it right now... > >>>> > >>>> I think that we can reconsider the LED handling implementation later, when > >>>> someone brings something better on the table. > >>> > >>> What worried me is the plan to expose this capability to user-space. > >>> If it's only a kernel-internal, we can fix it in the kernel and > >>> nothing else broken, but if it's a part of API, that's not easy. > >>> > >>> So, if any, I'd like to avoid exposing to the user-space at first. > >>> (But then it comes to the question how to deal with a case like AMD > >>> ACP...) > >> > >> I tried to propose a complete solution and the ACP was one strong reason for > >> this kernel / user space API. So without the user space support, it's just > >> a half solution for known issues. > >> > >> Frankly, I don't see any drawback or a problem even if we remove this API > >> later. > > > > Removing the user-space API is absolutely no-go. The only exception > > would be either the case really no one uses it or it's too buggy and > > unfixable. > > This is a special case. Even if those LED bits are ignored by kernel in > future, we expect to be replaced with another layer. Thus the functionality > must be retained. Well, we cannot know whether the replacement really happens or happened, and hence we never kill the old one. That's the problem. > >> The LED group bits are just informal for the user space and it's > >> expected to create the user controls tied to this LED functionality only in > >> alsa-lib/plugins at the moment. The kernel may return an error when the user > >> space tries to set those new bits when the API is deprecated and I believe > >> that the hardware design faults like AMD ACP (without the hardware mute) are rare. > > > > The experience tells us that users are creative enough to (ab)use a > > new ABI in any unexpected ways, and we have no control for it. So > > it's not about how alsa-lib is implemented but rather how ABI could be > > abused :) > > Ok, I don't have other ideas. I don't agree with your argumentation for this > particular case, where the functionality is marginal. Ideally, the AMD driver > may be recoded to use double-buffering and software mute switch, so we should > handle everything in the kernel space. My argument is that we're trying to add too much freedom just for this "marginal" problem. Honestly speaking, I would feel rather more comfortable if it were a kernel control element that just does trigger the LED like the original patch from AMD guys. Then you cannot do much wrong. OTOH, creating a virtual capture switch and let alsa-lib handling the software mute, while PA should ignores the soft-mute but dealing only with the assigned mute LED... Sounds too complex to me. thanks, Takashi