From mboxrd@z Thu Jan 1 00:00:00 1970 From: Leonard Crestez Subject: Re: [PATCH] ARM: dts: imx6sx-sdb: Remove cpufreq OPP override Date: Tue, 25 Apr 2017 20:23:24 +0300 Message-ID: <1493141004.3557.8.camel@nxp.com> References: <89cc7192100bdc9ce546bf6000446e629457ebc1.1493138693.git.leonard.crestez@nxp.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit Return-path: Received: from mail-by2nam01on0052.outbound.protection.outlook.com ([104.47.34.52]:47771 "EHLO NAM01-BY2-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1952010AbdDYRXd (ORCPT ); Tue, 25 Apr 2017 13:23:33 -0400 In-Reply-To: Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Fabio Estevam , Marek Vasut Cc: Shawn Guo , Sascha Hauer , Peter Chen , Anson Huang , "linux-pm@vger.kernel.org" , Viresh Kumar , "Rafael J. Wysocki" , linux-kernel , Fabio Estevam , "linux-arm-kernel@lists.infradead.org" , Christoph Fritz On Tue, 2017-04-25 at 14:02 -0300, Fabio Estevam wrote: > On Tue, Apr 25, 2017 at 2:02 PM, Fabio Estevam wrote: > > > > Hi Leonard, > > > > On Tue, Apr 25, 2017 at 1:57 PM, Leonard Crestez > > wrote: > > > > > > The board file for imx6sx-dbg overrides cpufreq operating points to use > > > higher voltages. This is done because the board has a shared rail for > > > VDD_ARM_IN and VDD_SOC_IN and when using LDO bypass the shared voltage > > > needs to be a value suitable for both ARM and SOC. > > > > > > This was introduced in: > > > > > > commit 54183bd7f766 ("ARM: imx6sx-sdb: add revb board and make it default") > > > > > > This only only applies to LDO bypass mode, a feature not present in > > > upstream. When LDOs are enabled the effect is to use higher voltages than > > > necesarry for no good reason. > > > > > > Setting these higher voltages can make some boards fail to boot with ugly > > > semi-random crashes, reminiscent of memory corruption. These failures > > > happen the first time the lowest idle state is used. Remove the OPP > > > override in order to fix those crashes. > > > > > > Signed-off-by: Leonard Crestez > > > > > > --- > > > It's not clear exactly why the crashes happen. Perhaps waking up from idle > > > draws more power than is available? Removing this override is a correct > > > change anyway so maybe there is no need to investigate deeper. > > Marek just sent a similar one a few minutes ago: > > http://lists.infradead.org/pipermail/linux-arm-kernel/2017-April/503230.html > Forgot to add Marek. Wow, that was literally 15 minutes before my patch. In my defense I did search the archives before starting to format the patch but it had not arrived yet. Anyway, that version also sets the supply for reg_arm and reg_soc. It is not necessary for fixing the crash I'm seeing but is good because it will result in the minimum voltage on VDD_ARM_SOC_IN rather than a fix 1375mv. I tested Marek's patch and it works fine on my rev B board (which otherwise fails to boot upstream). --  Regards, Leonard