linux-kernel - Re: [PATCH v3 3/7] PCI: imx6: Fix the regulator dump when link never came up

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Message-ID: <YXve+HlpEWOzZ+k3@sirena.org.uk>
Date:   Fri, 29 Oct 2021 12:46:00 +0100
From:   Mark Brown <broonie@...nel.org>
To:     Richard Zhu <hongxing.zhu@....com>
Cc:     Francesco Dolcini <francesco.dolcini@...adex.com>,
        "l.stach@...gutronix.de" <l.stach@...gutronix.de>,
        "bhelgaas@...gle.com" <bhelgaas@...gle.com>,
        "lorenzo.pieralisi@....com" <lorenzo.pieralisi@....com>,
        "jingoohan1@...il.com" <jingoohan1@...il.com>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        dl-linux-imx <linux-imx@....com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>
Subject: Re: [PATCH v3 3/7] PCI: imx6: Fix the regulator dump when link never
 came up

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.

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