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From: Mark Brown <broonie@kernel.org>
To: Andrei.Stefanescu@microchip.com
Cc: mark.rutland@arm.com, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org, gregkh@linuxfoundation.org,
	lgirdwood@gmail.com, robh+dt@kernel.org,
	linux-arm-kernel@lists.infradead.org,
	Claudiu.Beznea@microchip.com, Cristian.Birsan@microchip.com
Subject: Re: [RESEND PATCH v3 3/3] regulator: mcp16502: add regulator driver for MCP16502
Date: Wed, 12 Dec 2018 15:55:02 +0000	[thread overview]
Message-ID: <20181212155502.GD6920@sirena.org.uk> (raw)
In-Reply-To: <6a35df06-1309-f069-9b22-8c2cc5cca56e@microchip.com>


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On Wed, Dec 12, 2018 at 08:01:07AM +0000, Andrei.Stefanescu@microchip.com wrote:

> > This puts the device into low power mode when the suspend function gets
> > called but this might not be safe - devices using the regulator may not
> > be suspended yet so could still need full regulation.  Normally a GPIO
> > triggered transition like this would be being done by hardware as part
> > of the process of suspending the SoC.  Is there some reason to do this
> > manually?

> There is a line from the MPU (SHDN) which goes low only when the MPU
> turns off. That line is already connected to the PMIC and it differentiates
> between suspend-to-mem and standby. To switch to low-power, the PMIC must
> be controlled by the GPIO pin LPM.

> The suspend sequence is:
> - LPM pin goes high (PMIC enters Low-Power <-> Linux standby)
> - SHDN goes low (if target suspend state is mem) and then PMIC enters 
> HIBERNATE

This feels like it should be being controlled somewhere else, if it's
actually causing a change in the PMIC state it seems like it wants to be
done as late as possible in suspend to minimize the risks.  At the very
least suspend_late() for the driver seems appropriate.

Could you submit a version with this feature at least split out into a
separate patch please so we can apply the rest of the code while this is
discussed?

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WARNING: multiple messages have this Message-ID (diff)
From: Mark Brown <broonie@kernel.org>
To: Andrei.Stefanescu@microchip.com
Cc: robh+dt@kernel.org, lgirdwood@gmail.com, mark.rutland@arm.com,
	gregkh@linuxfoundation.org, Cristian.Birsan@microchip.com,
	Nicolas.Ferre@microchip.com, Claudiu.Beznea@microchip.com,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, devicetree@vger.kernel.org
Subject: Re: [RESEND PATCH v3 3/3] regulator: mcp16502: add regulator driver for MCP16502
Date: Wed, 12 Dec 2018 15:55:02 +0000	[thread overview]
Message-ID: <20181212155502.GD6920@sirena.org.uk> (raw)
In-Reply-To: <6a35df06-1309-f069-9b22-8c2cc5cca56e@microchip.com>

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On Wed, Dec 12, 2018 at 08:01:07AM +0000, Andrei.Stefanescu@microchip.com wrote:

> > This puts the device into low power mode when the suspend function gets
> > called but this might not be safe - devices using the regulator may not
> > be suspended yet so could still need full regulation.  Normally a GPIO
> > triggered transition like this would be being done by hardware as part
> > of the process of suspending the SoC.  Is there some reason to do this
> > manually?

> There is a line from the MPU (SHDN) which goes low only when the MPU
> turns off. That line is already connected to the PMIC and it differentiates
> between suspend-to-mem and standby. To switch to low-power, the PMIC must
> be controlled by the GPIO pin LPM.

> The suspend sequence is:
> - LPM pin goes high (PMIC enters Low-Power <-> Linux standby)
> - SHDN goes low (if target suspend state is mem) and then PMIC enters 
> HIBERNATE

This feels like it should be being controlled somewhere else, if it's
actually causing a change in the PMIC state it seems like it wants to be
done as late as possible in suspend to minimize the risks.  At the very
least suspend_late() for the driver seems appropriate.

Could you submit a version with this feature at least split out into a
separate patch please so we can apply the rest of the code while this is
discussed?

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  reply	other threads:[~2018-12-12 15:55 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-11 10:08 [RESEND PATCH v3 0/3] add support for MCP16502 PMIC Andrei.Stefanescu
2018-12-11 10:08 ` Andrei.Stefanescu
2018-12-11 10:08 ` Andrei.Stefanescu
2018-12-11 10:09 ` [RESEND PATCH v3 1/3] regulator: dt-bindings: add MCP16502 regulator bindings Andrei.Stefanescu
2018-12-11 10:09   ` Andrei.Stefanescu
2018-12-11 10:09   ` Andrei.Stefanescu
2018-12-11 10:09 ` [RESEND PATCH v3 2/3] MAINTAINERS: add maintainer for MCP16502 PMIC driver Andrei.Stefanescu
2018-12-11 10:09   ` Andrei.Stefanescu
2018-12-11 10:09   ` Andrei.Stefanescu
2018-12-11 10:09 ` [RESEND PATCH v3 3/3] regulator: mcp16502: add regulator driver for MCP16502 Andrei.Stefanescu
2018-12-11 10:09   ` Andrei.Stefanescu
2018-12-11 10:09   ` Andrei.Stefanescu
2018-12-11 16:47   ` Mark Brown
2018-12-11 16:47     ` Mark Brown
2018-12-12  8:01     ` Andrei.Stefanescu
2018-12-12  8:01       ` Andrei.Stefanescu
2018-12-12  8:01       ` Andrei.Stefanescu
2018-12-12 15:55       ` Mark Brown [this message]
2018-12-12 15:55         ` Mark Brown
2018-12-13 12:19         ` Andrei.Stefanescu
2018-12-13 12:19           ` Andrei.Stefanescu
2018-12-13 12:19           ` Andrei.Stefanescu
2018-12-13 16:21           ` Mark Brown
2018-12-13 16:21             ` Mark Brown

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