From: andrew-sh.cheng <andrew-sh.cheng@mediatek.com>
To: Viresh Kumar <viresh.kumar@linaro.org>
Cc: "Mark Rutland" <mark.rutland@arm.com>,
"Nishanth Menon" <nm@ti.com>,
srv_heupstream <srv_heupstream@mediatek.com>,
"linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>,
"Stephen Boyd" <sboyd@kernel.org>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"Rob Herring" <robh+dt@kernel.org>,
"Chanwoo Choi" <cw00.choi@samsung.com>,
"Kyungmin Park" <kyungmin.park@samsung.com>,
"MyungJoo Ham" <myungjoo.ham@samsung.com>,
"linux-mediatek@lists.infradead.org"
<linux-mediatek@lists.infradead.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"Matthias Brugger" <matthias.bgg@gmail.com>,
"Fan Chen (陳凡)" <fan.chen@mediatek.com>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>
Subject: Re: [v4, 7/8] cpufreq: mediatek: add opp notification for SVS support
Date: Fri, 18 Oct 2019 17:03:51 +0800 [thread overview]
Message-ID: <1571389431.27207.4.camel@mtksdaap41> (raw)
In-Reply-To: <20191017063102.4jirlphdxdydl2bm@vireshk-i7>
On Thu, 2019-10-17 at 12:01 +0530, Viresh Kumar wrote:
> On 16-10-19, 10:43, andrew-sh.cheng wrote:
> > This is due to SVS feature need to fix Vproc for calibration.
> > When SVS calibration, it want to disable all opp items, except one with
> > voltae 1.0V. (SVS will change the voltage field of that opp item, if the
> > corresponding voltage is not 1.0V)
> > In this way, SVS can make sure there is no other module, include
> > thermal, will change Vproc by DVFS driver.
> > After SVS calibration done, SVS will enable those disabled opp items
> > back.
>
> But why is this required to be done this way ? Why can't we just update the
> voltages without doing this disable/enable dance ?
>
This is because some opp items need voltage larger than 1.0V.
We cannot update the voltage to 1.0V.
If we don't disable these opp items, and DVFS policy want to set these
high frequencies, dvfs driver will set higher voltage to Vproc and SVS
calibration will be fail.
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next prev parent reply other threads:[~2019-10-18 9:04 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-13 13:31 [v4, 0/8] Add cpufreq and cci devfreq for mt8183, and SVS support Andrew-sh.Cheng
2019-08-13 13:31 ` [v4, 1/8] cpufreq: mediatek: change to regulator_get_optional Andrew-sh.Cheng
2019-08-19 9:51 ` Viresh Kumar
2019-08-13 13:31 ` [v4, 2/8] cpufreq: mediatek: add clock enable for intermediate clock Andrew-sh.Cheng
2019-08-19 9:50 ` Viresh Kumar
2019-08-13 13:31 ` [v4, 3/8] cpufreq: mediatek: Add support for mt8183 Andrew-sh.Cheng
2019-08-19 9:59 ` Viresh Kumar
2019-08-13 13:31 ` [v4, 4/8] dt-bindings: devfreq: add compatible for mt8183 cci devfreq Andrew-sh.Cheng
2019-08-13 13:31 ` [v4, 5/8] devfreq: add mediatek " Andrew-sh.Cheng
2019-08-13 13:31 ` [v4, 6/8] PM / OPP: Support adjusting OPP voltages at runtime Andrew-sh.Cheng
2019-08-19 11:18 ` Viresh Kumar
2019-11-01 8:08 ` Roger Lu
2019-11-05 6:56 ` Viresh Kumar
2019-08-22 13:51 ` Matthias Brugger
2019-08-13 13:31 ` [v4, 7/8] cpufreq: mediatek: add opp notification for SVS support Andrew-sh.Cheng
2019-08-20 3:39 ` Viresh Kumar
2019-10-16 2:43 ` andrew-sh.cheng
2019-10-17 6:31 ` Viresh Kumar
2019-10-18 9:03 ` andrew-sh.cheng [this message]
2019-10-18 9:53 ` Viresh Kumar
2019-08-13 13:31 ` [v4, 8/8] devfreq: mediatek: cci devfreq register " Andrew-sh.Cheng
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