Re: [PATCH] regulator: core: Allow for regulators that can't be read at bootup

[David Collins]

On 05/15/2018 03:07 PM, Douglas Anderson wrote:
> As discussed in the patches to try to support the RPMh regulators [1],
> the fact that regulators are write-only means that its driver's
> get_voltage_sel() should return an error code if it's called before
> any calls to set_voltage_sel().  This causes problems in
> machine_constraints_voltage() when trying to apply the constraints.

This problem specifically arises in the latest RPMh regulator patch [1] if
regulator-min-microvolt and regulator-max-microvolt are specified for a
VRM managed RPMh regulator device but the qcom,regulator-initial-microvolt
property is not provided.  Therefore, listing
qcom,regulator-initial-microvolt is a way to avoid regulator registration
issues.


> In this patch I propose the error code -ENOTRECOVERABLE.  In errno.h
> this error is described as "State not recoverable".

I'm fine with this constant.  Hopefully Mark is as well.


> If this patch is accepted then we'll need to update the latest RPMh
> regulator patch to return it.  The current patch returns -EINVAL which
> means that the regulator always fails.

I'll make this modification if needed.

Take care,
David

[1] https://lkml.org/lkml/2018/5/11/703

-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project