linux-kernel - Re: [PATCH] ARM: dts: imx6sx-sdb: Remove cpufreq OPP override

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Date:   Thu, 4 May 2017 19:43:45 +0800
From:   Shawn Guo <shawnguo@...nel.org>
To:     Peter Chen <peter.chen@....com>
Cc:     Leonard Crestez <leonard.crestez@....com>,
        Sascha Hauer <kernel@...gutronix.de>,
        Anson Huang <anson.huang@....com>,
        Robin Gong <yibin.gong@....com>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Fabio Estevam <fabio.estevam@....com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH] ARM: dts: imx6sx-sdb: Remove cpufreq OPP override

On Thu, Apr 27, 2017 at 01:17:12AM +0000, Peter Chen 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.
> >
> 
> Add Anson and Robin
> 
> This code has existed more than 2 years, it is strange why the bug has not reported both
> for internal user and external user. I run upstream kernel using imx6sx-sdb revB very often
> at recent years, but not meet this issue. How to trigger this unstable issue, anything needs
> to change at u-boot?

Per comments from Henri and Leonard, it sounds like the issue only
happens on RevC board?

Shawn