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 2EC8EC4167B for ; Mon, 7 Feb 2022 11:26:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To: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=FBmL6zweOISJo9hTsKNCRwavWRoszUcKiuFS6NBypMo=; b=N3yPngnOT/2n3L fqAo5SoIH8NEuy9pn5skxKIB9tj+JR5YydqDPjXGenbhl/hVdkk93SVmC82hn+5dEz54PLPrNP05T zGRuduvpG7gdHSP9nrY2XJK8dOBWneKMw6sbhURiSenBswDt/tXIreFW+4d/GxmSOgiQ8Z51T0R96 ZivQ1ZO2t0WaQrmkMBEDGdaKpQuJhEidPrk5plFc7GqPua4YcycJVqyC7PaUz3KkIAZDeQ98S5IJj 3f4vhGG8XV6rrk7fVSjL3OrdrJ3SIdL7eW0E0GiPuSa5AbhRuUP1wSwIHgY7CbcOPi86UFYfhcj+i 12+m34D7s51kWKVahb2g==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nH292-009yed-So; Mon, 07 Feb 2022 11:25:20 +0000 Received: from muru.com ([72.249.23.125]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nH28z-009yd6-V6 for linux-arm-kernel@lists.infradead.org; Mon, 07 Feb 2022 11:25:19 +0000 Received: from localhost (localhost [127.0.0.1]) by muru.com (Postfix) with ESMTPS id EB08280E1; Mon, 7 Feb 2022 11:24:52 +0000 (UTC) Date: Mon, 7 Feb 2022 13:25:14 +0200 From: Tony Lindgren To: Matthias Schiffer Cc: Rob Herring , Arnd Bergmann , Olof Johansson , soc@kernel.org, Vignesh Raghavendra , Tero Kristo , jan.kiszka@siemens.com, linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Nishanth Menon Subject: Re: [PATCH v2 1/2] arm64: dts: ti: k3-am65: disable optional peripherals by default Message-ID: References: <20220203140240.973690-1-matthias.schiffer@ew.tq-group.com> <20220204143108.653qk2ihnlhsr5aa@prior> <5944ba0ce568eaf507917799b1dfd89a3d0ca492.camel@ew.tq-group.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <5944ba0ce568eaf507917799b1dfd89a3d0ca492.camel@ew.tq-group.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220207_032518_068261_180B77C3 X-CRM114-Status: GOOD ( 17.49 ) 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: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org * Matthias Schiffer [220207 08:45]: > Generally I think that it's a bootloader's responsiblity to disable > unneeded devices - the kernel may not even have a driver for some > peripherals, leading to the same behaviour as a "disabled" status. For > this reason I believe that it should always be okay to set unneeded > devices to "disabled", and it should be considered a safe default. Not possible, think kexec for example :) How would the previous kernel even know what to disable if Linux has no idea about the devices? If there are issues you're seeing, it's likely a bug in some of the device drivers for not checking for the necessary resources like pinctrl for i2c lines. > I'm not sure what the consensus on these issues is. I'm more familiar > with NXP's i.MX and Layerscape SoCs, where it's common to have all > muxable peripherals set to "disabled" in the base DTSI, and a quick > grep through a few dts directories gives me the impression that this is > the case for most other vendors as well. This approach only works for SoCs that don't need the kernel to idle devices for runtime PM. Regards, Tony _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel