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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 3D8AEC3DA59 for ; Tue, 16 Jul 2024 12:17:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To: Content-Transfer-Encoding:Content-Type:MIME-Version:References:Message-ID: Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=7epGewsS+mJ+mnJ3Go9v/2WOXqDjSVE0Sbhq0kgoFuE=; b=XWdMi8YYywEz4DLEw6aAL5kK1v NMNq3zpz8A9jDEhq0edwZhDtyE6aPP8Ja/TINbh2Fu0si6gk4J/mnyVmIuUxTsho+kQWRcTz+a8TF AdjDYGxfGOy1rhtG73Y+iIDvR/duIbe7L0hn0UEtgXtp47Izqhfz0/onMGALol4VcOTz9kfTtNJfP fDIU2RfXgaymbCa7wm4eMUfnMYmNdJBXmR+AIiQ9e2PEPHrxzr7qMzZETulouyzuZNhE9lJun3wv3 od2GyNnJmnuZLIt4Qj1asak4L7yQV5XnECdy6lkIzBOdHuv81fOVJw0sr4KGnOUUIeFwSQ6ZKRSH+ ZSwqbiHA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1sTh7F-0000000ANqY-0rsT; Tue, 16 Jul 2024 12:17:09 +0000 Received: from madrid.collaboradmins.com ([46.235.227.194]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1sTh6u-0000000ANks-1cAy; Tue, 16 Jul 2024 12:16:49 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1721132204; bh=rJCw4t9lWh++5hHyvwrQaAK5GI2g8BPbimI06KKCYCc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=w7m0k+SOd8zofuFtNtIc8DFMSoyULF4p95gUiJGeTIL5tw51TDAON077i/HMOsTU6 zOdXEdeteWHcA02RTUO8Zp3feDbTDVuQjgBBHjO9TPxg+talhgoGiJmW9yMcrsd9HH gIP1Vm7UCtLOesfztNh+bgCCpMOrJ5HVxLnXtp5CNX3bRbHNzJXChaDnXcuhh3ntpl keGyoVsovW4QI+KO2k1cythhTcNMWGZ3bjcRDns/A6UzuhORe5q3Y8vFH2KEp296sR xQP8G3DP5PT2F904rJq9QPmA+mRSXWGMjUkG1VCi3UEY80gYUw6x9RwQ5gbbTxZ1Hl zHdqP2zFpdZTQ== Received: from notapiano (zone.collabora.co.uk [167.235.23.81]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (prime256v1) server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: nfraprado) by madrid.collaboradmins.com (Postfix) with ESMTPSA id CDD2A3781185; Tue, 16 Jul 2024 12:16:41 +0000 (UTC) Date: Tue, 16 Jul 2024 08:16:39 -0400 From: =?utf-8?B?TsOtY29sYXMgRi4gUi4gQS4=?= Prado To: AngeloGioacchino Del Regno Cc: Matthias Brugger , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Thomas =?utf-8?Q?Wei=C3=9Fschuh?= , Tzung-Bi Shih , kernel@collabora.com, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org Subject: Re: [PATCH RFC] arm64: dts: mediatek: mt8195-cherry: Remove keyboard-backlight node Message-ID: <96f91c0a-e693-45db-a664-1c396b14999e@notapiano> References: <20240715-cros-backlight-dt-probe-v1-1-0b5afe64c94b@collabora.com> <3dd2dcc9-5fbb-4384-985f-a61e26cc8a5f@collabora.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <3dd2dcc9-5fbb-4384-985f-a61e26cc8a5f@collabora.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240716_051648_590330_A421DEDE X-CRM114-Status: GOOD ( 31.88 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Jul 16, 2024 at 11:24:44AM +0200, AngeloGioacchino Del Regno wrote: > Il 15/07/24 18:09, Nícolas F. R. A. Prado ha scritto: > > Commit 970c3a6b7aa3 ("mfd: cros_ec: Register keyboard backlight > > subdevice") introduced support for detecting keyboard backlight > > fuctionality through communication with the ChromeOS EC. This means that > > the DT node is no longer used. Remove the unneeded node. > > > > Signed-off-by: Nícolas F. R. A. Prado > > --- > > Different CrosEC FW versions could potentially not support discovering > > the keyboard backlight functionality, but I've tested both a recent > > > > tomato_v2.0.23149-099cd3e539 tomato_15699.72.0 2024-01-03 > > > > and an old > > > > tomato_v2.0.10686-234e646fd8 tomato_14268.0.0 2021-10-07 > > > > version on mt8195-cherry-tomato and on both relying only on the > > discoverability works. I've tested on both tomato-r2 and tomato-r3. I > > have not tested on dojo, however, as I don't have access to it. > > > > Dojo will work anyway because those machines do share the same base FW... but > anyway, I'm not sure that this is the right thing to do. > > The commit that you mentioned says that it is meant to make that "work on machines > without specific ACPI or OF support for the keyboard backlight", but not that the > intention is to stop using either ACPI nor DT nodes for that. Yes, because as I understand it not every EC might support this protocol. So that commit just added an additional way to probe the keyboard backlight. So we don't need to stop using the DT to probe it. But in practice we have already stopped, as long as the EC supports the protocol (which from my testing is always for these platforms), since that is tried first. Meaning the DT node is now useless. The only point in keeping the DT node would be to use it as a fallback in case the discovery with the EC fails or breaks. But I have never seen a DT node be there just as fallback, so it doesn't feel right to me either. > > The DT kselftest is relatively young, and I suspect that anyway this is not the > only affected device, so the justification is only barely valid. I didn't include the failing test as part of the commit message proper as I don't think it should justify this change. I added it just to clarify my motivation. The test showed me that something unexpected was happening. After looking into it I thought that a DT node that is no longer used to probe has no point in staying around, so that's the justification that I added to the commit message. > > Don't misunderstand me, I'm not saying that I'm not okay with this, but I'd like to > have more opinions about this. > > If we choose to go this way, ideally we should remove this from all of the upstream > Chromebook devicetrees (not only MediaTek, clearly!) so that would require a bit > more effort to test here and there. Note that the cherry DT is the only DT upstream with the google,cros-kbd-led-backlight compatible. So it's really only tomato and dojo that need to be tested. Thanks, Nícolas