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From: <andrew-sh.cheng@mediatek.com>
Cc: Mark Rutland <mark.rutland@arm.com>, Nishanth Menon <nm@ti.com>,
	srv_heupstream@mediatek.com, linux-pm@vger.kernel.org,
	Stephen Boyd <sboyd@kernel.org>,
	Viresh Kumar <viresh.kumar@linaro.org>,
	"Rafael J . Wysocki" <rjw@rjwysocki.net>,
	Liam Girdwood <lgirdwood@gmail.com>,
	Rob Herring <robh+dt@kernel.org>,
	linux-kernel@vger.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-arm-kernel@lists.infradead.org,
	Matthias Brugger <matthias.bgg@gmail.com>,
	devicetree@vger.kernel.org
Subject: Re: [PATCH 09/12] devfreq: add mediatek cci devfreq
Date: Thu, 21 May 2020 16:52:35 +0800	[thread overview]
Message-ID: <1590051155.14062.3.camel@mtksdaap41> (raw)
In-Reply-To: <20200520123135.GD4823@sirena.org.uk>


On Wed, 2020-05-20 at 13:31 +0100, Mark Brown wrote:
> On Wed, May 20, 2020 at 11:43:04AM +0800, Andrew-sh.Cheng wrote:
> 
> > +	cci_df->proc_reg = devm_regulator_get_optional(cci_dev, "proc");
> > +	ret = PTR_ERR_OR_ZERO(cci_df->proc_reg);
> > +	if (ret) {
> > +		if (ret != -EPROBE_DEFER)
> > +			dev_err(cci_dev, "failed to get regulator for CCI: %d\n",
> > +				ret);
> > +		return ret;
> > +	}
> > +	ret = regulator_enable(cci_df->proc_reg);
> 
> The code appears to require a regulator (and I'm guessing the device
> needs power) so why is this using regulator_get_optional()?

Hi Mark,

Do you mean, why not use regulator_get_exclusive() or regulator_get()?
Because cci and cpu litter core shared buck, it cannot use
regulator_get_exclusive().
Because both cci and cpu want to tune voltage, it cannot use
regulator_get(), otherwise it will get dummy regulator even this buck
doesn't register.as regulator.

BR,
Andrew-sh.Cheng
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  reply	other threads:[~2020-05-21  8:53 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CGME20200520034324epcas1p3affbd24bd1f3fe40d51baade07c1abba@epcas1p3.samsung.com>
2020-05-20  3:42 ` [PATCH 00/12] Add cpufreq and cci devfreq for mt8183, and SVS support Andrew-sh.Cheng
2020-05-20  3:42   ` [PATCH 01/12] OPP: Allow required-opps even if the device doesn't have power-domains Andrew-sh.Cheng
2020-05-20 14:54     ` Matthias Brugger
2020-05-21  1:50       ` andrew-sh.cheng
2020-05-20  3:42   ` [PATCH 02/12] OPP: Add function to look up required OPP's for a given OPP Andrew-sh.Cheng
2020-05-20  3:42   ` [PATCH 03/12] OPP: Improve required-opps linking Andrew-sh.Cheng
2020-05-20  3:42   ` [PATCH 04/12] PM / devfreq: Cache OPP table reference in devfreq Andrew-sh.Cheng
2020-05-20  3:43   ` [PATCH 05/12] PM / devfreq: Add required OPPs support to passive governor Andrew-sh.Cheng
2020-05-20  3:43   ` [PATCH 06/12] PM / devfreq: Add cpu based scaling support to passive_governor Andrew-sh.Cheng
2020-05-28  5:03     ` Chanwoo Choi
2020-05-28  6:14     ` Chanwoo Choi
2020-05-28  7:17       ` Chanwoo Choi
2020-06-02 12:23         ` andrew-sh.cheng
2020-06-03  4:12           ` Chanwoo Choi
2020-06-02 11:43       ` andrew-sh.cheng
2020-06-03  4:07         ` Chanwoo Choi
2020-06-17  7:59           ` andrew-sh.cheng
2020-05-20  3:43   ` [PATCH 07/12] cpufreq: mediatek: Enable clock and regulator Andrew-sh.Cheng
2020-05-20  3:43   ` [PATCH 08/12] dt-bindings: devfreq: add compatible for mt8183 cci devfreq Andrew-sh.Cheng
2020-05-28  7:42     ` Chanwoo Choi
2020-06-17 12:05       ` andrew-sh.cheng
2020-05-20  3:43   ` [PATCH 09/12] devfreq: add mediatek " Andrew-sh.Cheng
2020-05-20 12:31     ` Mark Brown
2020-05-21  8:52       ` andrew-sh.cheng [this message]
2020-05-28  7:35     ` Chanwoo Choi
2020-05-28  8:00       ` Chanwoo Choi
2020-05-20  3:43   ` [PATCH 10/12] opp: Modify opp API, dev_pm_opp_get_freq(), find freq in opp, even it is disabled Andrew-sh.Cheng
2020-05-20  3:43   ` [PATCH 11/12] cpufreq: mediatek: add opp notification for SVS support Andrew-sh.Cheng
2020-05-20  3:43   ` [PATCH 12/12] devfreq: mediatek: cci devfreq register " Andrew-sh.Cheng
2020-05-20  4:10   ` [PATCH 00/12] Add cpufreq and cci devfreq for mt8183, and " Chanwoo Choi
2020-05-20  5:36     ` andrew-sh.cheng
2020-05-20  6:24       ` Chanwoo Choi
2020-05-20  7:10         ` andrew-sh.cheng
2020-05-20 14:53           ` Matthias Brugger
2020-06-15  7:31   ` Viresh Kumar

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