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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham 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 8C82CC282C4 for ; Mon, 4 Feb 2019 20:59:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 57B7020823 for ; Mon, 4 Feb 2019 20:59:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1549313978; bh=G6rx6Uox3aB/VE4hHKNJhzBK07fDVi1ALoT+Izhs1mM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=FUm2JA3MCMiT2YLFkdisr7zc7pAYOX0rhS0gBrpn/bJ0vXX5YWmKrAKfiiWTRTVXU BeP7J7+g7lSdZuj9tBymRQSqd4MSTBr+jGN7H840pqb8LI0Ru9YjrQT5huUDKvXyyU D84iasxcNVIR0F2Gju9Wbh6VGiG6FtZiH8gz/vgM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727985AbfBDU7g (ORCPT ); Mon, 4 Feb 2019 15:59:36 -0500 Received: from heliosphere.sirena.org.uk ([172.104.155.198]:49238 "EHLO heliosphere.sirena.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725855AbfBDU7g (ORCPT ); Mon, 4 Feb 2019 15:59:36 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sirena.org.uk; s=20170815-heliosphere; h=In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=/Cypi6Nm7kLGCX7Mv9+7bjDSldyEsPRepQ/bGOPmy+c=; b=uxP/fvBgkGE7RaleOq3Ij+hCT zwOhp2ceRcSWonY8PQZdrskzqHi3OAcihF3LBKeZcrK4nFlZ7jEqLX98XhGWbnPYfWOJP7IirEIFV 9VeOBxm59GnoJGGqyfyMizUFq9hmT0ftrPFAYT6C+ZoKETvRpVEmvF/VNe/NtXR+/vgDY=; Received: from [109.236.136.146] (helo=finisterre.ee.mobilebroadband) by heliosphere.sirena.org.uk with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1gqlL1-0006Wj-4r; Mon, 04 Feb 2019 20:59:31 +0000 Received: by finisterre.ee.mobilebroadband (Postfix, from userid 1000) id 9C224440082; Mon, 4 Feb 2019 20:59:30 +0000 (GMT) Date: Mon, 4 Feb 2019 21:59:30 +0100 From: Mark Brown To: Bjorn Andersson Cc: Niklas Cassel , Jorge Ramirez , Andy Gross , David Brown , Rob Herring , Mark Rutland , linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Khasim Syed Mohammed Subject: Re: [PATCH] arm64: dts: qcs404: evb: Fix voltages for s5 and l3 Message-ID: <20190204205930.GK23441@sirena.org.uk> References: <20190125232954.26166-1-bjorn.andersson@linaro.org> <32b8136d-3acb-66e9-948c-ee8903b91401@linaro.org> <20190129224652.GB11349@centauri.lan> <20190204104347.GD23441@sirena.org.uk> <20190204160337.GG2387@tuxbook-pro> <20190204182321.GH23441@sirena.org.uk> <20190204192510.GZ31919@minitux> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="BFVE2HhgxTpCzM8t" Content-Disposition: inline In-Reply-To: <20190204192510.GZ31919@minitux> X-Cookie: Murphy was an optimist. User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --BFVE2HhgxTpCzM8t Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Mon, Feb 04, 2019 at 11:25:10AM -0800, Bjorn Andersson wrote: > On Mon 04 Feb 10:23 PST 2019, Mark Brown wrote: > > On Mon, Feb 04, 2019 at 08:03:37AM -0800, Bjorn Andersson wrote: > Okay, I don't see a big problem with expecting the DT to only contain > values that the hardware can actually do. I do however see that > machine_constraints_voltage() has been changes to expect the driver to > return -ENOTRECOVERABLE when we don't have a way to query the voltage > during probe. > So there's a risk of this breaking compatibility with older dtb files on > other boards. We will have to do some more verification on this. That's basically only going to affect Qualcomm hardware FWIW, I had thought that such devices didn't manage to probe with upstream before that change either but I could be misremembering. > > > regulator framework be made to round down to the previous valid step > > > instead of up? > > We definitely don't want to round voltages down, it is vastly more > > common for devices to experience problems like brownouts if they go > > under voltage so it'd be more likely to cause harm than good. > We're 2mV off in this case, but it could have been way off. So I'm good > with this position. Never mind that that's 2mV assuming the regulator has perfect accuracy and there's headroom. For something like this it's likely not a problem but some high current things (especially CPUs or anything like that) are operating on thin margins. --BFVE2HhgxTpCzM8t Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAlxYp68ACgkQJNaLcl1U h9DL1Qf9ED2ORN4Cuibho/qUCZ5Vmyq+ZZRNIMfcx+diIXcc2K8kfEGbQRNOcaOC XYV9xfdv0kf6wJmw/KSn78iOhBac6VpZDTV2HDytsNd97JKExcBB3w9KficyBWNz 3CxQIBsyrzrwXsAaXQwbqqSabaUL4GMdQaK2LutuzIti4mjT8bUNSzSvP55kK+PK vp9IwHvDjIJppc0YyupME4lRsWHUAuK+TmJuTWfsuQOMwGPe9SUbwoBV/FU3QzJ9 p+1iRIDWN/G9TkRgo4MqhzAL1L1mTpOB0S9xk392sG4J8L4N7xk1Z6ZCBsT8sVXP CglfiH5s9zVjbXlKyehlSRbgPqSskg== =eM4M -----END PGP SIGNATURE----- --BFVE2HhgxTpCzM8t--