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From: Leonard Crestez <leonard.crestez@nxp.com>
To: Mark Brown <broonie@kernel.org>
Cc: Liam Girdwood <lgirdwood@gmail.com>,
	Viresh Kumar <viresh.kumar@linaro.org>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	"Shawn Guo" <shawnguo@kernel.org>,
	Sascha Hauer <kernel@pengutronix.de>,
	Robin Gong <yibin.gong@nxp.com>,
	Anson Huang <Anson.Huang@nxp.com>,
	Irina Tirdea <irina.tirdea@nxp.com>,
	Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Fabio Estevam <fabio.estevam@nxp.com>,
	"Octavian Purdila" <octavian.purdila@nxp.com>,
	<linux-pm@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>,
	<devicetree@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [RFC 5/8] regulator: anatop: fix min dropout for bypass mode
Date: Tue, 28 Mar 2017 14:52:46 +0300	[thread overview]
Message-ID: <1490701966.3546.24.camel@nxp.com> (raw)
In-Reply-To: <20170324125438.5wy3r2mr3g5eaxvy@sirena.org.uk>

On Fri, 2017-03-24 at 12:54 +0000, Mark Brown wrote:
> On Wed, Mar 22, 2017 at 06:53:07PM +0200, Leonard Crestez wrote:
> > +	if (anatop_reg->bypass)
> > +		anatop_reg->rdesc.min_dropout_uV = 0;
> > +	else
> > +		anatop_reg->rdesc.min_dropout_uV = LDO_MIN_DROPOUT_UV;
> No, this is completely broken - you can't expect to randomly change hthe
> regulator description at runtime behind the back of the framework and
> expect things to work.  If there is a need to do this we need an
> interface for getting the current value and a way to notify of changes.
> 
> That said I would not expect the dropout voltage to be considered at
> all when the regulator is bypassed, since the regulator is not
> regulating it doesn't need any headroom.

It's a more complex solution but this could be handled in the core instead.
Basically the core would treat min_dropout_uV as zero if the regulator is
currently in bypass mode.

In theory a function could be added in regulator_ops to ask a regulator driver
what requirements it has for its supply but this does not seem necessary.

  reply	other threads:[~2017-03-28 11:53 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-03-22 16:53 [RFC 0/8] ARM: imx: Upstream fsl,ldo-bypass Leonard Crestez
2017-03-22 16:53 ` [RFC 1/8] ARM: imx: gpc: Do not print error message for EPROBE_DEFER Leonard Crestez
2017-03-22 16:53 ` [RFC 2/8] cpufreq: imx6q: Fix handling EPROBE_DEFER from regulator Leonard Crestez
2017-03-23  4:33   ` Viresh Kumar
2017-03-22 16:53 ` [RFC 3/8] cpufreq: imx6q: Set max suspend_freq to avoid changes during suspend Leonard Crestez
2017-03-23  4:34   ` Viresh Kumar
2017-03-28 20:03     ` Leonard Crestez
2017-03-28 20:50       ` Rafael J. Wysocki
2017-03-28 22:23         ` Rafael J. Wysocki
2017-03-22 16:53 ` [RFC 4/8] regulator: core: Check enabling bypass respects constraints Leonard Crestez
2017-03-24 12:52   ` Mark Brown
2017-03-28 12:39     ` Leonard Crestez
2017-03-28 16:47       ` Mark Brown
2017-03-28 19:49         ` Leonard Crestez
2017-04-06 18:52           ` Mark Brown
2017-04-07 10:51             ` Leonard Crestez
2017-04-07 11:22               ` Mark Brown
2017-04-13 20:46                 ` Leonard Crestez
2017-03-22 16:53 ` [RFC 5/8] regulator: anatop: fix min dropout for bypass mode Leonard Crestez
2017-03-24 12:54   ` Mark Brown
2017-03-28 11:52     ` Leonard Crestez [this message]
2017-03-22 16:53 ` [RFC 6/8] regulator: core: Add regulator_is_bypass function Leonard Crestez
2017-03-24 12:55   ` Mark Brown
2017-03-28 14:53     ` Leonard Crestez
2017-03-22 16:53 ` [RFC 7/8] cpufreq: imx6q: Initialize LDO bypass Leonard Crestez
2017-03-22 17:09   ` Lucas Stach
2017-03-22 17:48     ` Leonard Crestez
2017-03-22 18:00       ` Lucas Stach
2017-03-22 16:53 ` [RFC 8/8] ARM: dts: imx6qdl-sabresd: Enable fsl,ldo-bypass Leonard Crestez
2017-03-22 17:13   ` Lucas Stach
2017-03-29 13:32     ` Leonard Crestez

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