linux-kernel - Re: [PATCH] Revert "PM / OPP: Don't assume platform doesn't have regulators"

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] [day] [month] [year] [list]

Message-ID: <CAJZ5v0gVxoCD4E7cHec9iFJb8_9G4USyMDJ9mrBNvFB_Pf=uzw@mail.gmail.com>
Date:   Thu, 8 Dec 2016 00:29:15 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     Rafael Wysocki <rjw@...ysocki.net>,
        Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        Stephen Boyd <sboyd@...eaurora.org>,
        Lists linaro-kernel <linaro-kernel@...ts.linaro.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Jon Hunter <jonathanh@...dia.com>, swarren@...dia.com,
        Thierry Reding <treding@...dia.com>
Subject: Re: [PATCH] Revert "PM / OPP: Don't assume platform doesn't have regulators"

On Wed, Dec 7, 2016 at 11:31 AM, Viresh Kumar <viresh.kumar@...aro.org> wrote:
> This reverts commit ef3caabee9691386e6801ea92150e37277db9c7a.
>
> The commit was based on the assumption that a platform with voltages
> specified with individual OPPs, would have registered a regulator as
> well in order to do full DVFS.
>
> That assumption is broken by the Tegra124 platform.
>
> For Tegra124, the voltage is not scaled via a direct call to the
> regulator subsystem because the DFLL directly controls the I2C interface
> that controls the voltage. The DFLL essentially figures out the max
> frequency for a given voltage. So to run at a particular frequency, the
> DFLL continuously adjusts the voltage in a control loop fashion to get
> the desired frequency.
>
> Following are the logs from: NVIDIA Tegra124 Jetson TK1
>
>   cpufreq: cpufreq_online: CPU0: Running at unlisted freq: 696000 KHz
>   cpu cpu0: dev_pm_opp_set_rate: Regulator not registered with OPP core
>   cpufreq: __target_index: Failed to change cpu frequency: -22
>   ------------[ cut here ]------------
>   kernel BUG at drivers/cpufreq/cpufreq.c:1235!
>
> Fix these by reverting the offending commit.
>
> Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
>
> ---
> Rafael, you can simply drop the patch if that is easier for you.

Done.

Thanks,
Rafael