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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Tue, 25 Apr 2017 14:02:04 -0300
From:   Fabio Estevam <festevam@...il.com>
To:     Leonard Crestez <leonard.crestez@....com>
Cc:     Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <kernel@...gutronix.de>,
        Peter Chen <Peter.Chen@....com>,
        Anson Huang <Anson.Huang@....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 <linux-kernel@...r.kernel.org>,
        Fabio Estevam <fabio.estevam@....com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        Christoph Fritz <chf.fritz@...glemail.com>
Subject: Re: [PATCH] ARM: dts: imx6sx-sdb: Remove cpufreq OPP override

Hi Leonard,

On Tue, Apr 25, 2017 at 1:57 PM, Leonard Crestez
<leonard.crestez@....com> 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 <leonard.crestez@....com>
>
> ---
> 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