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From: Dmitry Osipenko <digetx@gmail.com>
To: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
	Mark Brown <broonie@kernel.org>,
	Marek Szyprowski <m.szyprowski@samsung.com>
Cc: linux-kernel@vger.kernel.org, Liam Girdwood <lgirdwood@gmail.com>,
	Lucas Stach <l.stach@pengutronix.de>,
	Krzysztof Kozlowski <krzk@kernel.org>,
	linux-samsung-soc@vger.kernel.org,
	Viresh Kumar <viresh.kumar@linaro.org>,
	Kamil Konieczny <k.konieczny@samsung.com>
Subject: Re: [PATCH] regulator: core: Skip balancing of the enabled regulators in regulator_enable()
Date: Tue, 8 Oct 2019 18:02:36 +0300
Message-ID: <be8d3280-9855-ed18-b2ab-d7fb28d80b82@gmail.com> (raw)
Message-ID: <20191008150236.KdN2f25LLkHLmbVyvU2wfcYAPmzFdMLFQOUKEoZpP88@z> (raw)
In-Reply-To: <86b9b4b5-cca5-9052-7c87-c5679dfffff4@samsung.com>

08.10.2019 16:24, Bartlomiej Zolnierkiewicz пишет:
> 
> On 10/8/19 2:47 PM, Mark Brown wrote:
>> On Tue, Oct 08, 2019 at 02:38:55PM +0200, Marek Szyprowski wrote:
>>
>>> Then if I get it right, the issue is caused by the commit 7f93ff73f7c8 
>>> ("opp: core: add regulators enable and disable"). I've checked and 
>>> indeed reverting it fixes Peach Pi to boot properly.

Yes, please note that the "ww_mutex" patch didn't change the original logic and only
rearranged the code a tad.

 The question is if
>>> this is desired behavior or not?
>>
>> That doesn't seem ideal - either it's redundant for regulators that need
>> to be marked as always-on anyway or it's going to force the regulators
>> on when a device could do runtime PM (eg, if the same code can run on
>> something like a GPU which can be turned off while the screen is off or
>> is displaying a static image).
> 
> Commit 7f93ff73f7c8 ("opp: core: add regulators enable and disable")
> currently can be safely reverted as all affected users use always-on
> regulators. However IMHO it should be possible to enable always-on
> regulator without side-effects.
> 
> When it comes to setting regulator constraints before doing enable
> operation, it also seems to be possible solution but would require
> splitting regulator_set_voltage() operation on two functions:
> 
> - one for setting constraints (before regulator_enable() operation)
> 
> - the other one actually setting voltage (after enable operation)
> 
> Unfortunately this is much bigger task and doesn't seem to be -rc
> time material so I'm in favor of just applying Marek's fix as it is
> for now.

That OPP patch caused the same problem for the NVIDIA Tegra20 CPUFreq driver (in-progress)
and I resolved it in the coupler's code [0]. Perhaps the generic coupler could do the same
thing by assuming that min_uV=current_uV until any consumer sets the voltage, i.e. if
regulator_check_consumers(min_uV=0) returns min_uV=0.

[0] https://lkml.org/lkml/2019/7/25/892

  parent reply index

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CGME20191008101720eucas1p2e0d1bca6e696848bf689067e05620679@eucas1p2.samsung.com>
2019-10-08 10:17 ` Marek Szyprowski
2019-10-08 10:17   ` Marek Szyprowski
2019-10-08 11:50   ` Mark Brown
2019-10-08 11:50     ` Mark Brown
2019-10-08 12:01     ` Marek Szyprowski
2019-10-08 12:01       ` Marek Szyprowski
2019-10-08 12:06       ` Mark Brown
2019-10-08 12:06         ` Mark Brown
2019-10-08 12:38         ` Marek Szyprowski
2019-10-08 12:38           ` Marek Szyprowski
2019-10-08 12:47           ` Mark Brown
2019-10-08 12:47             ` Mark Brown
2019-10-08 13:24             ` Bartlomiej Zolnierkiewicz
2019-10-08 13:24               ` Bartlomiej Zolnierkiewicz
2019-10-08 15:02               ` Dmitry Osipenko [this message]
2019-10-08 15:02                 ` Dmitry Osipenko
2019-10-08 16:15                 ` Mark Brown
2019-10-08 16:15                   ` Mark Brown
2019-10-08 17:05                   ` Dmitry Osipenko
2019-10-08 17:05                     ` Dmitry Osipenko
2019-10-08 17:17                     ` Mark Brown
2019-10-08 17:17                       ` Mark Brown
2019-10-08 18:00                       ` Dmitry Osipenko
2019-10-08 18:00                         ` Dmitry Osipenko
2019-10-08 18:07                         ` Mark Brown
2019-10-08 18:07                           ` Mark Brown
2019-10-09 10:29                           ` Marek Szyprowski
2019-10-09 10:29                             ` Marek Szyprowski
2019-10-09 14:13                             ` Mark Brown
2019-10-09 14:13                               ` Mark Brown
2019-10-10  7:29                               ` Viresh Kumar
2019-10-10  7:29                                 ` Viresh Kumar
2019-10-10 10:19                               ` Marek Szyprowski
2019-10-10 10:19                                 ` Marek Szyprowski
2019-10-10 13:55                                 ` Mark Brown
2019-10-10 13:55                                   ` Mark Brown
2019-10-17 10:29                                   ` Marek Szyprowski
2019-10-08 15:48               ` Mark Brown
2019-10-08 15:48                 ` Mark Brown
2019-10-08 16:02                 ` Bartlomiej Zolnierkiewicz
2019-10-08 16:02                   ` Bartlomiej Zolnierkiewicz
2019-10-08 16:21                   ` Mark Brown
2019-10-08 16:21                     ` Mark Brown

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