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=-3.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no 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 2183CC433F5 for ; Fri, 17 Sep 2021 11:44:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EFBBB61212 for ; Fri, 17 Sep 2021 11:44:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241908AbhIQLpd (ORCPT ); Fri, 17 Sep 2021 07:45:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54434 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234669AbhIQLpc (ORCPT ); Fri, 17 Sep 2021 07:45:32 -0400 Received: from metis.ext.pengutronix.de (metis.ext.pengutronix.de [IPv6:2001:67c:670:201:290:27ff:fe1d:cc33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B09C0C061574 for ; Fri, 17 Sep 2021 04:44:10 -0700 (PDT) Received: from gallifrey.ext.pengutronix.de ([2001:67c:670:201:5054:ff:fe8d:eefb] helo=[IPv6:::1]) by metis.ext.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1mRCHo-0008GX-7t; Fri, 17 Sep 2021 13:44:08 +0200 Message-ID: <9bcf7b749dca57d42aa2e7afd88b5a26f3eeff2a.camel@pengutronix.de> Subject: Re: [PATCH] arm64: dts: imx8mm-kontron-n801x-som: do not allow to switch off buck2 From: Lucas Stach To: Heiko Thiery , Frieder Schrempf Cc: devicetree@vger.kernel.org, Guido =?ISO-8859-1?Q?G=FCnther?= , Fabio Estevam , Shengjiu Wang , "Angus Ainslie (Purism)" , linux-kernel@vger.kernel.org, Krzysztof Kozlowski , Joakim Zhang , Michael Walle , Rob Herring , NXP Linux Team , Pengutronix Kernel Team , Shawn Guo , Sascha Hauer , linux-arm-kernel@lists.infradead.org Date: Fri, 17 Sep 2021 13:44:04 +0200 In-Reply-To: References: <20210915120325.20248-1-heiko.thiery@gmail.com> <7e7ee4244ababc0a46e0875222c7e37d@walle.cc> <898fd5e0-2073-3689-89b6-2c5071773786@kontron.de> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.40.4 (3.40.4-1.fc34) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 2001:67c:670:201:5054:ff:fe8d:eefb X-SA-Exim-Mail-From: l.stach@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: devicetree@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org Am Freitag, dem 17.09.2021 um 09:28 +0200 schrieb Heiko Thiery: > Hi Frieder, > > Am Mi., 15. Sept. 2021 um 14:09 Uhr schrieb Frieder Schrempf > : > > > > On 15.09.21 14:05, Michael Walle wrote: > > > Am 2021-09-15 14:03, schrieb Heiko Thiery: > > > > The buck2 output of the PMIC is the VDD core voltage of the cpu. > > > > Switching off this will poweroff the CPU. Add the 'regulator-always-on' > > > > property to avoid this. > > > > > > Mh, have this ever worked? Is there a commit which introduced a regression? > > > > Yes, this did work before, even without 'regulator-always-on'. I > > currently don't understand why this is needed. The regulator is > > referenced in the CPU nodes as 'cpu-supply'. This should be enough to > > not disable it as long as the CPU is up. > > I rechecked that with 5.11, 5.10 and 5.9 and I see on all of them the > same issue: > > [ 31.716031] vdd-5v: disabling > [ 31.719032] rst-usb-eth2: disabling > [ 31.722553] buck2: disabling > > While on that I tried to compare with other boards and see that they > also have the cpu-voltage marked as "regulator-always-on". The only > exception in dts/freescale is in imx8mq-librem5-devkit.dts [1] that > has not set this property. > > I agree with you and don't understand why this is happening. Has > anyone else an explanation? > > [1] https://elixir.bootlin.com/linux/latest/source/arch/arm64/boot/dts/freescale/imx8mq-librem5-devkit.dts#L319 > Maybe your kernel config is missing the cpufreq driver, so you don't have a consumer of the regulator? Marking the regulator as always-on seems like the right thing to do, you don't want to depend on a consumer showing up to make sure that your CPU voltage isn't cut... Regards, Lucas