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 90DF4C433EF for ; Mon, 7 Feb 2022 06:56:07 +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=5PUKm9AOQRx8Ey6B8Fgjvu1inbzDkdNPSlpITp9ww+c=; b=IlX0BbbDPIw1Cb v9fYZ9O+d+Au40gtg5OBtKHbvJ+gRbGGA6NTb6EBIvLXtOAGCDh1tLLaDZB4taeOMw/LiJv21yFyy Bn4hDALSqs7mMInfdkcp4VFtQDcY3RP7lc13p1x3iBP0ExUfPAx50ohY/iAlueCUr+dqxjG2PIpHF YPg55A2FMMutAwZGSsMPUv3glNnU6niQkBijPAExGvX2I1FgZwnLY1xnhvl3rllRH8zUs674dCgYt z9ngoCS/g9CjqcSdi0z3DirnECWWzTN2G1tjSzg0h93MJm0GQZfJgcMgKZbWS2GxVOkUre8mUVPyb lLw2+bpbqtX3sU4mxc3w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nGxv9-009BnG-TU; Mon, 07 Feb 2022 06:54:44 +0000 Received: from muru.com ([72.249.23.125]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nGxv6-009Bmx-Sk for linux-arm-kernel@lists.infradead.org; Mon, 07 Feb 2022 06:54:42 +0000 Received: from localhost (localhost [127.0.0.1]) by muru.com (Postfix) with ESMTPS id 4FDBE80E1; Mon, 7 Feb 2022 06:54:16 +0000 (UTC) Date: Mon, 7 Feb 2022 08:54:37 +0200 From: Tony Lindgren To: Nishanth Menon Cc: Matthias Schiffer , 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 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> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20220204143108.653qk2ihnlhsr5aa@prior> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220206_225441_008943_AEB11B01 X-CRM114-Status: GOOD ( 17.53 ) 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 Hi, * Nishanth Menon [220204 14:30]: > Rob, Tony, Arnd, SoC maintainers, > > On 15:02-20220203, Matthias Schiffer wrote: > > All peripherals that require pinmuxing or other configuration to work > > should be disabled by default. Dependent DTS are adjusted accordingly. Disabling SoC internal devices by default is not a good policy. The devices are available even if not pinned out. Disabling device by default causes runtime PM to not work as the kernel will completely ignore the disabled devices. And this means you add a dependency to some certain version of a bootloader for PM to work. Additionally tagging devices as disabled by default (and then again re-enabling them in the board specific dts files) is just pointless churn and bloat. See for example commit 12afc0cf8121 ("ARM: dts: Drop pointless status changing for am3 musb") :) If you really want to disable some devices for memory usage or other reasons, do it in the board specific dts files. > https://lore.kernel.org/linux-arm-kernel/20201112183538.6805-1-nm@ti.com/ > reversal all over again. > > Is there a specific pattern we are intending to use here? Because, if we > are going down this path (which would be a major churn across multiple > downstream trees as well) - I'd rather have this as a documented > standard and not just a TI approach and will need to be done across all > K3 devices. > > Are you aware of such a documented guideline, rather than "word of > mouth"? Maybe I have'nt looked deep enough, but checking.. For SoCs that don't implement runtime PM the policy can be different without causing any harm. But for any SoCs implementing runtime PM, an unknown state from the bootloader is not going to work. Regards, Tony _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel