From: Dmitry Osipenko <digetx@gmail.com>
To: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Rob Herring <robh+dt@kernel.org>,
Thierry Reding <thierry.reding@gmail.com>,
Jonathan Hunter <jonathanh@nvidia.com>,
linux-pm@vger.kernel.org,
Vincent Guittot <vincent.guittot@linaro.org>,
Rafael Wysocki <rjw@rjwysocki.net>,
Stephen Boyd <sboyd@kernel.org>, Nishanth Menon <nm@ti.com>,
Stephan Gerhold <stephan@gerhold.net>,
devicetree@vger.kernel.org, linux-tegra@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/3] ARM: tegra: Pass multiple versions in opp-supported-hw property
Date: Tue, 1 Sep 2020 16:21:30 +0300 [thread overview]
Message-ID: <603071ec-6ae4-7e34-26e4-f64065b01ee0@gmail.com> (raw)
In-Reply-To: <20200831110408.a6lwivim4w4jtkdc@vireshk-i7>
31.08.2020 14:04, Viresh Kumar пишет:
> On 31-08-20, 12:54, Dmitry Osipenko wrote:
>> It's not clear to me how it could be applicable to the Tegra CPU OPP
>> because Tegra depends on a combination of SPEEDO + PROCESS versions.
>>
>> It's not like all voltages are the same for all OPPs that have the same
>> PROCESS ID, otherwise it indeed would be nice to have
>> "opp-microvolt-process0", but unfortunately this variant is not suitable
>> for Tegra because some freqs have different voltages using the same
>> PROCESS ID and the same applies to the SPEEDO ID.
>
> How exactly do you know what voltage belongs to a particular OPP ?
From these tables:
https://nv-tegra.nvidia.com/gitweb/?p=linux-2.6.git;a=blob;f=arch/arm/mach-tegra/tegra2_dvfs.c;hb=l4t/l4t-r16-r2#l157
https://nv-tegra.nvidia.com/gitweb/?p=linux-2.6.git;a=blob;f=arch/arm/mach-tegra/tegra3_dvfs.c;hb=l4t/l4t-r16-r2#l148
> opp@216000000 {
> clock-latency-ns = <400000>;
> opp-supported-hw = <0x0F 0x0003>;
> opp-hz = /bits/ 64 <216000000>;
> opp-microvolt-fast-process0 = <750000 750000 1125000>;
> opp-microvolt-slow-process0 = <750000 850000 1125000>;
>
> };
>
> opp@312000000 {
> clock-latency-ns = <400000>;
> opp-supported-hw = <0x0F 0x0003>;
> opp-hz = /bits/ 64 <312000000>;
> opp-microvolt-fast-process0 = <750000 750000 1125000>;
> opp-microvolt-slow-process0 = <750000 850000 1125000>;
> };
>
> You can make any combinations of such names that come from speedo,
> process, or something else. If you can get this done as a fixed
> formula then it is workable.
>
IIUC, there is no fixed formula for Tegra, at least I don't see it. For
example, if you'll take a look at the 1300MHz OPP of Tegra30, then you
could see that this freq has a lot of voltages each depending on
specific combination of SPEEDO+PROCESS versions.
next prev parent reply other threads:[~2020-09-01 13:22 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-26 11:50 [PATCH 0/3] opp: Allow opp-supported-hw to contain multiple versions Viresh Kumar
2020-08-26 11:50 ` [PATCH 1/3] dt-bindings: " Viresh Kumar
2020-08-26 11:50 ` [PATCH 2/3] " Viresh Kumar
2020-08-26 16:59 ` Stephan Gerhold
2020-08-28 7:38 ` Dmitry Osipenko
2020-08-26 11:50 ` [PATCH 3/3] ARM: tegra: Pass multiple versions in opp-supported-hw property Viresh Kumar
2020-08-28 7:37 ` Dmitry Osipenko
2020-08-31 4:39 ` Viresh Kumar
2020-08-31 7:54 ` Dmitry Osipenko
2020-08-31 8:41 ` Viresh Kumar
2020-08-31 9:54 ` Dmitry Osipenko
2020-08-31 11:04 ` Viresh Kumar
2020-09-01 13:21 ` Dmitry Osipenko [this message]
2020-09-02 5:23 ` Viresh Kumar
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