On Fri, Oct 29, 2021 at 03:58:41AM +0000, Richard Zhu wrote:

> > The driver should undo any enables it did itself, it should not undo any
> > enables that anything else did which means it should never be basing
> > decisions on regulator_is_enabled().  While the regulator may not be
> > shared in the particular board you're looking at it may be shared in other
> > systems.

> [Richard Zhu] Understood. Thanks.
> Can I disabled this regulator in PCIe probe failure handler without the
>  regulator_is_enabled() check?

If the driver called regulator_enable() (and that didn't return an
error) it can always call regulator_disable() as many times as it called
regulator_enable(), no need to check if the regulator is still enabled.  
When the driver hasn't successfully called regulator_enable() it
shouldn't call regulator_disable() even if the regualtor is enabled.
This means that after your driver has enabled the regulator it can just
disable it but between the regulator_get() and regulator_enable() it
shouldn't do that.