Re: [RESEND PATCH v3 3/3] regulator: mcp16502: add regulator driver for MCP16502

From: Mark Brown
Date: Wed Dec 12 2018 - 10:55:20 EST

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

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

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