From: Dmitry Osipenko <digetx@gmail.com>
To: Lucas Stach <l.stach@pengutronix.de>,
Viresh Kumar <viresh.kumar@linaro.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>,
Rob Herring <robh+dt@kernel.org>,
Thierry Reding <thierry.reding@gmail.com>,
Jonathan Hunter <jonathanh@nvidia.com>,
Nishanth Menon <nm@ti.com>, Stephen Boyd <sboyd@kernel.org>,
Marcel Ziswiler <marcel.ziswiler@toradex.com>,
linux-tegra@vger.kernel.org, linux-pm@vger.kernel.org,
devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH v2 01/17] OPP: Allow to request stub voltage regulators
Date: Sun, 28 Oct 2018 15:58:25 +0300 [thread overview]
Message-ID: <bd3a57ee-6131-22bb-1954-3d97bba5276a@gmail.com> (raw)
In-Reply-To: <1540568255.2245.11.camel@pengutronix.de>
On 10/26/18 6:37 PM, Lucas Stach wrote:
> Am Freitag, den 26.10.2018, 15:03 +0300 schrieb Dmitry Osipenko:
> [...]
>>> On the other hand, the tegra20 cpufreq driver is common across a lot of boards.
>>> What will happen if the DT for some of the boards isn't correct and missed the
>>> necessary regulator node ?
>>
>> AFAIK, there is assumption that bootloader should setup regulators in
>> a way that kernel could work properly at max clock rates. Otherwise
>> things won't work.
>
> This isn't true. The assumption is that the bootloader sets up the
> regulators such that stable operation at the CPU speed used by the
> bootloader is guaranteed.
>
> Often the bootloader doesn't know about specific SKUs, so drives things
> at a rate/voltage that is safe across all SKUs [1], in which case the
> bootloader is totally unaware of the voltage needed to run the CPU at
> highest possible clock frequency.
>
> Regards,
> Lucas
>
> [1] http://git.denx.de/?p=u-boot.git;a=commit;h=2364e151e432b4ccf32dc9e6147121253d4ff86d
>
Oh, okay. Thank you for pointing at [1], though the assumption is true for T20.
I agree that it's better not to rely on configuration left from bootloader in general.
next prev parent reply other threads:[~2018-10-28 12:58 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-21 20:54 [RFC PATCH v2 00/17] CPUFREQ OPP's, DVFS and Tegra30 support by tegra20-cpufreq driver Dmitry Osipenko
2018-10-21 20:54 ` [RFC PATCH v2 01/17] OPP: Allow to request stub voltage regulators Dmitry Osipenko
2018-10-22 5:36 ` Viresh Kumar
2018-10-22 11:29 ` Dmitry Osipenko
2018-10-22 11:32 ` Viresh Kumar
2018-10-22 12:12 ` Dmitry Osipenko
2018-10-24 6:41 ` Viresh Kumar
2018-10-26 12:03 ` Dmitry Osipenko
2018-10-26 15:37 ` Lucas Stach
2018-10-28 12:58 ` Dmitry Osipenko [this message]
2018-10-29 6:53 ` Viresh Kumar
2018-10-30 15:48 ` Dmitry Osipenko
2018-10-21 20:54 ` [RFC PATCH v2 02/17] soc/tegra: fuse: Export tegra_get_chip_id() Dmitry Osipenko
2018-10-21 21:33 ` Dmitry Osipenko
2018-10-21 20:54 ` [RFC PATCH v2 03/17] dt-bindings: cpufreq: Add binding for NVIDIA Tegra20/30 Dmitry Osipenko
2018-11-05 21:30 ` Rob Herring
2018-11-08 16:48 ` Dmitry Osipenko
2018-10-21 20:54 ` [RFC PATCH v2 04/17] cpufreq: tegra20: Support OPP, thermal cooling, DVFS and Tegra30 Dmitry Osipenko
2018-10-21 20:54 ` [RFC PATCH v2 05/17] ARM: tegra: Create tegra20-cpufreq device on Tegra30 Dmitry Osipenko
2018-10-21 20:54 ` [RFC PATCH v2 06/17] ARM: dts: tegra20: Add CPU Operating Performance Points Dmitry Osipenko
2018-10-21 20:54 ` [RFC PATCH v2 07/17] ARM: dts: tegra30: " Dmitry Osipenko
2018-10-21 20:54 ` [RFC PATCH v2 08/17] ARM: dts: tegra20: colibri: Setup voltage regulators for DVFS Dmitry Osipenko
2018-10-21 20:54 ` [RFC PATCH v2 09/17] ARM: dts: tegra20: harmony: " Dmitry Osipenko
2018-10-22 15:33 ` Stephen Warren
2018-10-22 22:59 ` Dmitry Osipenko
2018-10-21 20:54 ` [RFC PATCH v2 10/17] ARM: dts: tegra20: paz00: " Dmitry Osipenko
2018-10-21 20:54 ` [RFC PATCH v2 11/17] ARM: dts: tegra20: seaboard: " Dmitry Osipenko
2018-10-21 20:54 ` [RFC PATCH v2 12/17] ARM: dts: tegra20: tamonten: " Dmitry Osipenko
2018-10-21 20:54 ` [RFC PATCH v2 13/17] ARM: dts: tegra20: ventana: " Dmitry Osipenko
2018-10-21 20:54 ` [RFC PATCH v2 14/17] ARM: dts: tegra30: apalis: " Dmitry Osipenko
2018-10-21 20:54 ` [RFC PATCH v2 15/17] ARM: dts: tegra30: beaver: " Dmitry Osipenko
2018-10-21 20:55 ` [RFC PATCH v2 16/17] ARM: dts: tegra30: cardhu: " Dmitry Osipenko
2018-10-21 20:55 ` [RFC PATCH v2 17/17] ARM: dts: tegra30: colibri: " Dmitry Osipenko
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