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 B9E6BC433DB for ; Wed, 24 Feb 2021 07:13:02 +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 E2A7D64E79 for ; Wed, 24 Feb 2021 07:13:01 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E2A7D64E79 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 29F331679; Wed, 24 Feb 2021 08:12:10 +0100 (CET) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa0.perex.cz 29F331679 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=alsa-project.org; s=default; t=1614150780; bh=CP7nCpTw9Bcn7WecRMOQs9J+P4anmYNqESJYKdgUa8E=; h=Date:From:To:Subject:In-Reply-To:References:Cc:List-Id: List-Unsubscribe:List-Archive:List-Post:List-Help:List-Subscribe: From; b=dVR9qgPK7n4NC+mAu2sR+9sLSTD1Fm759mY/6wbNeG5MgZ4OJelEkr5EKEo1UXrlt p88RbzTzo6cd1lCjVuDE5gUv4m/Kz5yzBw2t0a/NCcKCLQt0VOhKhbsIOyEboY21mS i+FNuntyBaYGGskcsAh6A5wfasUIYZtxtcvBdAxY= Received: from alsa1.perex.cz (localhost.localdomain [127.0.0.1]) by alsa1.perex.cz (Postfix) with ESMTP id B75E1F8016C; Wed, 24 Feb 2021 08:12:09 +0100 (CET) Received: by alsa1.perex.cz (Postfix, from userid 50401) id 115E8F8022B; Wed, 24 Feb 2021 08:12:08 +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 B59AEF80161 for ; Wed, 24 Feb 2021 08:12:05 +0100 (CET) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa1.perex.cz B59AEF80161 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 9509EAEA8; Wed, 24 Feb 2021 07:12:04 +0000 (UTC) Date: Wed, 24 Feb 2021 08:12:04 +0100 Message-ID: From: Takashi Iwai To: Jaroslav Kysela Subject: Re: [RFC 2/2] ASoC: rt5670: Add LED trigger support In-Reply-To: <5c6a21c1-7107-3351-25be-c007b0b946d3@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> 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 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. > 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 :) Takashi