From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from madrid.collaboradmins.com (madrid.collaboradmins.com [46.235.227.194]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6597919AD51; Tue, 16 Jul 2024 16:06:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=46.235.227.194 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721145995; cv=none; b=obCBbTzdNCZ5hjAVctCrWj6ZL0EatQ3FkjVHt+K4piDit3uLrs6Is+2TASJOZ0PBt2PCkrF8OBXvQrmQcs66+ELFa5sd/m5GNdiMj25RSY17/04zbzK9DkTfvTQLLe67QjuG+C/tlS19kjRDianYdrrH23aabX27Kk/8P5q4mxM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721145995; c=relaxed/simple; bh=gI21/Txq0/V8Mood/7WNX4+a8nWK19FWuXo1RHgcBlQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=glRjUtpvOTL/dC6h9nHk9f+9AbpKpiloikvLgTxS4HEVefkt0BFjsINtRWuKAxGLsrkp7fFbaK9OTYuePyr0gQOjqALuW7Zz3cSqYMc5zAw8l15gCcF1V3IZJqJ89sU3OWTXnjrJN2748enQDn3Zwgtxa5JhoXK2xXTNtQl6vT0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=collabora.com; spf=pass smtp.mailfrom=collabora.com; dkim=pass (2048-bit key) header.d=collabora.com header.i=@collabora.com header.b=N4CqeFe8; arc=none smtp.client-ip=46.235.227.194 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=collabora.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=collabora.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=collabora.com header.i=@collabora.com header.b="N4CqeFe8" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1721145991; bh=gI21/Txq0/V8Mood/7WNX4+a8nWK19FWuXo1RHgcBlQ=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=N4CqeFe8PNc3O+xfgpqGJQFUDEW+QKrrwmE1npMejRElOw2F71TZo63D/Z4iJ7Caj qklrx7vdRHrdCwPtgmHeqiEYtDApNOGRZooDnolD1wrfNTnui/d68Q8am6HMse0SDb J1+TMDsGtPuvLq4LL5fkNV9sZRduAwbYKqjI7GEGecd1FDvOuAL5+p2hMNdzTi0eNb VxBpM1dipIovxmrsn8NK5nscLTmFHq7r+Ut8eiCN5wt9JbNKx+0IUO4A8xWgAvzvQ/ S9RAQ7XQPJRu7K/GyhgJKhS8axETw3pI5vgDaJl68aEFDxQVUIn+h/om7qBbXKAglg obIuxqnflsjmA== Received: from [100.113.186.2] (cola.collaboradmins.com [195.201.22.229]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: kholk11) by madrid.collaboradmins.com (Postfix) with ESMTPSA id 18C8237821CD; Tue, 16 Jul 2024 16:06:31 +0000 (UTC) Message-ID: Date: Tue, 16 Jul 2024 18:06:30 +0200 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFC] arm64: dts: mediatek: mt8195-cherry: Remove keyboard-backlight node To: =?UTF-8?B?TsOtY29sYXMgRi4gUi4gQS4gUHJhZG8=?= Cc: Matthias Brugger , Rob Herring , Krzysztof Kozlowski , Conor Dooley , =?UTF-8?Q?Thomas_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 References: <20240715-cros-backlight-dt-probe-v1-1-0b5afe64c94b@collabora.com> <3dd2dcc9-5fbb-4384-985f-a61e26cc8a5f@collabora.com> <96f91c0a-e693-45db-a664-1c396b14999e@notapiano> From: AngeloGioacchino Del Regno Content-Language: en-US In-Reply-To: <96f91c0a-e693-45db-a664-1c396b14999e@notapiano> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Il 16/07/24 14:16, Nícolas F. R. A. Prado ha scritto: > 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. > Perfect. Let's remove it then, possibly with fire ;-) Can you please send the patch without the RFC tag? Also add my R-b, so that I'll remember that I've already checked that patch for when I'll be able to pick it. Reviewed-by: AngeloGioacchino Del Regno Cheers!